Today I got a little of both, when I won with black against Grandmaster Lars Karlsson (elo 2466), a Swedish player. Not a super-Grandmaster, admittedly, but still a dangerous player with an expected score above 90% against me (I am rated in the 2050 range. Here is the game with minimal commentary.
5' blitz, Internet Chess Club
After a not-well-known opening, a complex position has arisen on the board. The closed nature of the center invites players to take the initiative on either wing. White tried to get something started on the queenside with 10.a3, intending 11.b4 and the gain of space and an attack at the base of black's pawn chain, but it is not yet clear that such a plan is useful. So both players take some time to better evaluate the opponent's intentions...
Intending to exchange in c3 and picking up the a3 pawn after Bxc3. White parries the threat by exchanging in e4.
The white-squared black bishop is expendable. If white exchanges it, black places a very strong knight in e4, with prospects of a king-side attack.
An inaccurate move in my opinion. I have not bothered to check my evaluation with a chess engine, but this move appears to me a serious weakening of the black squares near the white king's shelter. Probably better was 17.c5 Bc7 18.b4, expanding on the queenside.
17. ..., Bg3
If 19.Re2 instead, Nf4 would follow with gain of time. As a result of white's pawn expansion in the center, black dominates in the dark squares. The bishop attack on the Re1 is less troubling a worry with respect to the general domination of the kingside.
White cannot avoid this pawn sacrifice. If 20.Rc3 Bf4! threatening to take the Nd2 and at the same time to invade with Qg3-h2. If instead 20.Qe2 Nf4 and the rook is lost, or 20.Re2 Nf4 with the same result.
A blunder, losing the Bd2. However, white's position is already compromised. 21.Re2 was perhaps best, but then 21..., Ng3 would still win black the exchange (22.Rf2 Be3 pinning the rook); furthermore, black also had 21....,Qg3 22.Nf3 Be4 with a winning attack.
A clean win with a grandmaster always sets me in a good mood for the rest of the evening!