So I was gladdened to see that Aronian Topalov game from round 7 of the London Chess Classic. Topalov played a strange (but by no means unknown) line of the Symmetrical English, where his knight moves 6 times before move 10. The logic behind this is the disrupt the White king, forcing it to move a couple of times, and preventing White from castling. Of course if I was showing this to a class of juniors I'd be waving my hands around at this point saying "and White wins", when of course this isn't quite true. White had a slight advantage, but it still took some energetic play from Aronian (and a pawn sacrifice) to convert. If you had to point the finger at any one move, then 20 ... Rd8 is the real culprit, allowing White to win the pawn on g5 and establish his queen on a strong square. After that it was all pretty straightforward for Aronian, and Topalov resigned just before his position was about to get wrecked by an exchange sac on c6.
Aronian,Levon - Topalov,Veselin [A34]
London Chess Classic Olympia, London (7.5), 11.12.2015