Without further ado:

Avada Kedavra (droodrog) vs Korea Starcraft Players (hunter tri-healer)
Score: 0-3 (Match details)
Video: POV Hawkn (Paladin)

Last tournament's winner vs the lowest ranked team on the tournament. What should have been a clean walkover, turned out to be greatest surprise of the first round. Even though there is no real counter comping on 5s, like evidently there is in 3s & 2s, where counter comping is abundant and most of the matches are decided when the gates open, line-ups do have advantages and disadvantages in 5s. In current metagame, probably the most skewed match-up, where the most significant advantages and disadvantages meet, is droodrog versus tri-healer hunter. It's really droodrog's Achilleus' heel, I'd rate the chances for the hunter team as high as 70-30, given equal level skill & teamwork.
When the brackets first went live, Avada Kedavra's captain Coold asked why did they get their probably hardest match-up as first, and they were a bit demoralized due to it having to fight against such hash odds just to stay on the winner's bracket. That combined with a busy week and having hard time training versus tri-healers on ladder games (due to not getting to fight any, since all tri-healers were significantly lower rated than AK) were probably key issues in AK's downfall.

Few snippets from KSP's hunter:
[mctatt] well we played like shit the week before in rated and therefor went down from standing 12 to standing 45, and we became last seeded, and AK winning last tour we where scheduled to play them, with out setup we have quite big win chance vs rmpwd, its just like 3v3 vs rmp, control rogue, survive burst, and thats what pretty much happened
[mctatt] i don't know if they played 100% or not just because of meeting our setup
[mctatt] and about the games, well we got the rogue out every game and we pretty much got the optimal start, one time by flare and the other by Goza throw a throwing-weap at him

Disco Raving Mummies (ench sham tri-healer) vs Cool Azshalleros (2345)
Score: 1-3 (Match details)

Without having a warlock to ravage, what DRM's setup is custom tailored to do, they succumbed to the old cookie-cutter setup of the German team. Dual melee vs a frost-mage isn't really something kid's ought to see, it's not pretty, and for once, the mage definitely isn't on the suffering end.
They didn't go down without a fight though, and managed to squeeze a single round from CA, before being out-kited by Najoua's Frostnovas and Cone of Colds.

Cowboys from Sweden (droodrog) vs Shake N Baked (2346)
Score: 1-3 (Match details)

From theorycraft's point of view, droodrog holds a small (something like 55-45) advantage over 2346, mainly due to their potential to both keep the opposing elemental shaman constantly in check while successfully training the warlock. This something that other setups would love to do, but just lack the tools to do so, usually resulting in bloodshed and carnage when the shaman gets the few second window it needs to discharge over 10k worth damage.
Now if the shaman is contained and dispelled, with means like constant tongues and a healthy amount of interrupts when he is trying to get casts off, he will be reduced to two-dimensional purge & buff bot. Even though purge spam is nothing to laugh about, it's something a priest could do too, and not a strong reason enough to justify bringing a shaman on board. Having the key class that should be the one tipping the scales to your favor nullified, while you're bleeding out both mana and cooldowns to keep another player alive drops the chances of winning significantly. Unless the shaman's team can do something to break the vicious cycle, it's a long and hard uphill battle towards running out of mana.

However this is something Hubris & co managed to pull off against Raphiron's Cowboys (if you look at the match screenshots, you wont see Hubris there, since he was playing his 2nd paladin, Teizuya, who has superior gear. Talk about love for the class).
Even though none of the games was a clear walkover, and SnB had to fight for each and every one of the wins, their preparation showed. The extensive training via ladder games against the multitudes of different droorogs as well as having an impressive lineup of arena veterans from previous season's top teams definitely helped them to overcome the bit inexperienced, yet gifted, CFS (they're a mix of transferees from different BG's united).

Few snippets from SnB's paladin:
[Hubris|Keeper] With a proper game plan for once, which allowed me to actually be in the game without getting CC'd to kingdom come, we managed to come out on top in the end
[Hubris|Keeper] Raphiron's team played alright, could've done better I suppose
[Hubris|Keeper] Granted, since they haven't played with each other for that long, except Dave/Raphiron
[Hubris|Keeper] There were bound to be mistakes
[Hubris|Keeper] On both sides of the fence, of course
[Hubris|Keeper] We didn't play flawlessly either, though
[Hubris|Keeper] Yeah, at the end of the day, their mistakes vs ours, and we came on top

Ocean Madness (hunter tri-healer) vs Nihilum Arena (hunter/shaman)
Score: 1-3 (Match details)

Even though Ocean Madness couldn't replicate with Nihilum what KSP did to AK, they proved they're not in this tourney just to look pretty and fill a spot while taking a dive without a fight. They managed to draw out the first 3 games versus Hammee & co's super-dps setup, which is a rather large feat by itself already, but they also managed to grab one of those rounds, really making Nihilum pay for each game.
Somewhat of an indicator of how clutch these games were, is that Nihi's priest Phixus only had only few thousand of damage dealt each game, meaning he only got to do one or two burns per game, if none at all. This from someone who's recognized as one of the most, if not the most, aggressive priest with manaburn in the battlegroup is simply put, huge. He used to empty out rival priests' manapools while only throwing mendings and shields in the process, and this was still when they didn't have bloodlust on their paladin to cover for healing. Talk about insane pressure by OM.

Few snippets from Nihilum's warrior:
(Hammee) We expected the games to be quite easy
(Hammee) It turned out to be hell
(Hammee) couldn't burst anything down, and the damage they were doing on our priest with their 2 melee was insane
(Hammee) But we played pretty lolish
(Hammee) Phixus managed to PI cherez one game, Slot forgot to use heroism the last game
(Hammee) You don't need to mention that though
(Hammee) I'd like to add
(Hammee) I'm really not happy about our setup though
(Hammee) Especially since we're meeting shaman/lock in phase2, which is a huge pain in the ass to win
(Hammee) it just that this setup is gonna be so much harder to get trough the tournament then if we just played hunter/lock

Nagas (war/hun/lock/rsham/pala) vs Four Kings (mage/lock)
Score: 3-1 (Match details)

An interesting clash of setups, Nagas play something that's relatively uncommon and unique while 4K has an oldschool setup that was quite triumphant back in season 2. Even though 4K has small advantage with being able to force Nagas' paladin to spam cleanse instead of healing through out the games with spammable CC's, bloodlust and shaman healing (as long as mana holds) should be enough to counter that disadvantage. I really couldn't say which team would had the advantage setup-wise, though past experiences have shown that Nagas have a superior teamwork compared to other top contenders.

Nagas' hunter & team leader was kind enough to sum up the games:
(nagatastic) First game: We were sleeping and not really prepared on their insane pressure on Buggelina and controll on Chriztian, so lost the first one.
(nagatastic) Second game: Dont have that one frapsed and i dont really remember much more then that Jebzig died and now we knew how they played.
(nagatastic) Third game: Both me and Paralol had some lucky crits and they just couldnt keep up with the healing and Jebzig died really fast.
(nagatastic) Fourth game: Dahl used his 2 blocks and were oom so both me and paralol focused him and he died seconds after that. Then I died 5-10 seconds after Dahl but we won anyway because both Mskin and Thelmir were oom and Chriztian had 5-6k mana left.

(ID`Vilu) frapsed the other games then?
(nagatastic) ye got fraps on all games except the second one
(nagatastic) well thats why we dont want to release the frapsed games, dont really want to give out our tactics
(nagatastic) maby after the tournament tho

And a statement from Nagas' warrior:
(paralol) me + wf = win
(ID`Vilu) he also called bloodlust a tactic, he's a joke cracker, ain't he!
(paralol) It's so much more than just bloodlust!
(paralol) It's WF!

Dont daze me bro (droodrog) vs MovieLÓL (2346)
Score: 3-1 (Match details)

MovieLOL's priest might have cost their team the match, having had lag related problems for the past few weeks, finally culminating in MovieLOL having to forfeit the remaining games to DDMB from a 1-2 position. Hopefully Athene & co can continue their games lag free in the LB, since I honestly think they could go far in this tournament as long their shaman Navar is playing on his normal level.

DDMB's priest & team leader was kind enough to sum up the games:
(Meths) well our 1st game, which we lost, I tried going really offensive and got drained, with nowhere to LoS on ruins
(Meths) 2nd game we just did the basic tactic, zerg their lock
(Meths) and same with 3rd game
(Meths) :)
(Meths) make sure freedom isn't up on their lock, and keep him dry of buffs
(Meths) for quick dispell of BoP / freedom etc
(Meths) straight forward shit rly
(Meths) massive much cc and win
(ID`Vilu) ./target lock /zerg /zerg some more /??? /profit?
(Meths) lol
(Meths) pretty much

Kammen Goes to Hollywood (2346) vs WE RLY CARE (droodrog)
Score: 1-3 (Match details)

The new guys got more or less stomped, while being able squeeze a single victory in Blade's Edge, where the weaknesses of Shader's combat/assasination -build combined with earthbind totem kite really shine. Three root brakers against an infinitely spammable AoE snare, in a map where there's always a room to kite only gives a limited time frame to get the job done, which is rather difficult versus bloodlusted healing.

ID Gaming TitanPoker (drainburn) vs I AR TANKER (2346)
Score: 3-1 (Match details)
Video: POV Lta (Priest)

Ever since shamans' got their watershield buffed, they became as 'immune' to mana burning and draining abilities as life-tapping warlocks are, swinging the balance of power a bit more in 2346 favor. Simply put, it's just not worth the effort it takes to first bring a shaman to a state of oom, and then keeping him there when you cannot put a pet on him, requiring constant burning when even the burns proc the watershield. Combined with the burst potential of bloodlusted & PI'd elemental shaman, it's rather demanding to keep up with the pressure a good 2346 can generate via constant DPS, targets swaps and lust burning without having bloodlust of one's own. While still trying to stay ahead in the managame.

Full match report with and FRAPS coming.