What opening should I play?

Tomorrow is the last round of a tournament I'm playing in.  At present, I have a perfect score- 4/4.  Tomorrow, I'm playing against a 2000-ish strength player (I'm 1900).  He has 3.5/4 right now.  As long as I don't lose, I win the tournament.  I'm white.  I like sharp, tactical openings.  He likes to positionally squeeze the opponent. 

Can someone tell me what first move I should play, then also what variations to play against the most popular replies?  Thanks!

1.d4  2...Bf4 and the London system. The London is perfect to play for a win with the draw in hand. If he doesnt take you seriously... all of a suddden his king can come under fire.

Read what IM John Cox writes in his book "dealing with d4 deviations" :

Cox : "It would be silly not to be honest -This is not the sharpest opening chess has to offer. Whites system is immensely solid and I am afraid black just doesnt have a sound aggressive option."

The only thing is that you say you are a sharp tactical player. But The London system can serve well both for the positional player and the aggressive kings attacker.

Just by playing this sytem your oponent may start to take risks to win and it could backfire easily against the London system.He has to win and faces the London. Not easy for black.

Yeah, I've looked at the London, and it looks to be the kind of thing I'm looking for in this game.  But what's my plan if ...g6 and ...Bg7 with black playing a KID formation?  I think the bishop on f4 looks pretty silly after ...d6, and will only serve to be a target.  He'll probably play the KID as he usually does anyway- what's white's plan of attack then?

The most basic rule of sports is when in a championship situation don't change your game. Play your best at what you know best.

I wish my Oklahoma Sooners would do that. They lost 3 national championship football games because they made changes to their game before the big game.

Dance with the one that brought you! If you still lose it just means your opponent is better than you. You can't count on gimmicks.

When facing a stronger player, play the opening you know best and play for the win. If it won't work out, then there's still the chance that it'll be a draw and not a loss.

These are two mistakes that one can make together:

- playing an opening that you don't have experience with

- playing for a draw

and if you're going to make them both together it will probably end in a loss. I've made them myself recently ... I have a mid-1300 rating OTB and played a mid-1400 rated opponent. I played the French which is an opening I knew well, but when he played the exchange variation, I played some moves from a grandmaster's blog where he wrote they would be perfectly safe (Bd6, Bf5, Ne7, Nc6, f6 I think). I've never played this setup before, I then missed some tactics and lost. I've played the French exchange variation before as black, where I didn't try to achieve a "safe" setup and instead attacked, they were all draws.

if you like playing aggressively then stick with e4 because that is the most tactical opening arround

not that experienced at chess but i am at other sports. and as a few people have mentioned, stick to what you have trained and prepare for.  It has boed well for myself and my colleugues, we hold a number of UK titles.(boxing etc..) million miles away from chess in some ways but not in this i believe.

London is good, but I find london boring. You develop, get good middlegame, no counterplays, and often draw. It's very boring, but very strong. It's too solid, you don't get to have strong attack, only defence and so on and so on. I'd rather lose a very sharp opening and be proud of how much effort i put in than winning a very boring game that i almost fell asleep. Chess is suppose to be a fun game so all my openings often are sharp. For me, I don't care about losing, I care about:

1) If the game was fun or not?

2) If I fully thought throughout the game or not?

3) If I tried my best or not.

No offense but london boring. Instead I prefre you people to play e4. I dont prefre you to play gambits becoz most gambits, black can compensate so not a good choice. Play openings like ruy lopez against e5. Just try to find a fun opening to play. e4 suits me best but d4 is also a choice only if you dont play a boring opening like london. Perhaps queens gambit will suit you people best!