Sergash: This was the second game opposing John Arni Nilssen and Magnus Carlsen, the first one having taken place at the Troll Masters in Gausdal, in January of that same year. In this game, Carlsen was playing White and had lost in 22 moves against Nilssen's Sicilian Defense.
John Arni Nilssen is born in 1974 and thus was 26 or 27 years old when he played the actual game, while Carlsen was 10 years old.
Nilssen is a member of the Faroe Islands Chess Federation (Denmark) and became an international master in 2006.
I went through the game with the program Stockfish 7 - 64 bits POPCNT.
<18...Bxc5?!> We often tell beginners not too study openings too much, but rather know the general principles (centre, piece development, castling sooner than later etc.). Here, we are still in the theory! But the move played is inferior.
Instead there were 18...a5 19.c6 Bd6 (Olivier Renet (2480) vs Gilles Miralles (2360), France Championship 1986, Playoffs, round 2, draw) 20.Nd4! =
Also 18...g5!? Cedric Paci (2301) vs Anna Rudolf (2242), Marianske Lazne IM (Czech Republic) 2008, B2, round 4, 0-1