I'm representing the US right now at the World Junior (under 20) Championship in Athens. I have 6/8 so far and there are still 5 rounds to go. Today was the first day that I played against a Grandmaster; in previous rounds I always played a lower-rated player. In those rounds I was on an annoying pattern where I would play relatively high-rated players (over 2350) with black and lower players (under 2350) with white, which is the exact opposite of what I want. But in round 8 I was lucky and got a second white in a row, against Yaroslav Zherebukh (2629) of Ukraine, the tournament's no. 3 seed.
We reached the following position which was part of my opening preparation:
Here Black played 16...Rd8, forcing White's queen to retreat.
17. Nd6! Bxe5 18. Nxe5 Rxd6 19. Qf4
Turns out I didn't have to retreat the queen after all. I got a strong attack for the pawn, as I had worked out on my computer long before.
My game the previous round was also interesting. I was happy with how I played in the middlegame and I won a bishop for 2 pawns. But then I blew it by losing all my pawns. It was uncannily similar to my round 6 game. In that game I was also up a piece, and somehow managed to blunder away all of my pawns. But unlike this one, I was still able to win in that game, with bishop, knight and rook versus bishop and knight.
Now after winning against the highest-rated player I have played so far, guess who I will play? A 2100-rated player! Mark Lapidus, my opponent for round 9, will be the lowest rated player I have played. However he is also the champion of Estonia. He also defeated a GM in round 8, with black to boot.
You can read more about the tournament at http://wjcc2012.chessdom.com/.