Krush gained a measure of fame both inside and outside chess circles during the well-publicized "Kasparov versus The World" chess competition in 1999. Garry Kasparov played the white pieces and the Internet public voted on moves for the black pieces, guided by the recommendations of Krush and three other young chess experts. On the tenth move, Krush suggested a stunning novelty, for which the World Team voted. Kasparov said later that he lost control of the game at that point, and wasn't sure whether he was winning or losing.
In addition to discovering a new move, Krush displayed great patience, tact, and generosity while participating in the bulletin board discussion of the game. Due to her social skill and tireless work on behalf of the World Team, she gradually became the focus of all the team's analytical efforts. The analysis tree she maintained gained considerable authority, and the recommendations therein were chosen by the team for more than twenty consecutive moves. Even grandmasters rated considerably higher than her began making primary reference to her analysis tree.
Thanks to Krush's efforts, the team worked in a more coordinated fashion than in any Internet game before or since. Unfortunately, on the 58th move, her recommendation was inexplicably delayed from appearing on the MSN website, and the team voters chose an objectively weaker move. Microsoft denied any failure on their part. Kasparov later published a "forced win" even against the better move proposed by Krush, and while computer analysis subsequently showed that his position was indeed won, it also showed that his analysis contained errors which would have allowed a draw, had he not discovered the mistakes in time.
Controversy aside, the game was a splendid brawl, and the outcome was in doubt for more than fifty moves. Kasparov had high praise for the World Team, and said that the game required more sustained effort from him than any other event in which he has participated, including preparing for World Championship matches. Irina's endgame analysis pushed back the frontiers of KQP vs KQP endgame knowledge, and her opening novelty has forced grandmasters to abandon Kasparov's opening line in favor of a different move order.
Krush won the 1998 US Women's Chess Championship at the age of 14, but has not participated in the event since for various reasons. She holds the title of International Master (IM) and has one of three tournament results (norms) necessary to qualify for the International Grandmaster (GM) title.
SmartChess Online maintains an extensive Web page tracking Krush's career.