Young Nodirbek Abdusattorov proved to possess steelier nerves under pressure, beating Wesley So, 2.5-1.5, in the opening day of the semifinals of the Chess.com Champions Chess Tour Thursday in cold Toronto, Canada.

World champion Magnus Carlsen of Norway likewise had to run through the gauntlet, winning by a sudden-death armageddon, to defeat Fabiano Caruana, 3-2, in the other semis match.

Both Americans, So and Caruana need to win in Friday's new set of best-of-four rapid games assignments to stave off elimination and keep their separate hopes of forcing a deciding clincher alive.

Abdusattorov knows it is still an uphill battle in the hunt for the $200,000 top purse. Against So, who beat and relegated him to the survivors' bracket in the eliminations, the crafty teenager knows he has to work doubly hard.

"This is my first match win against Wesley. It feels great but it will be decided tomorrow. I think Wesley was not in good shape today so I think he will give me a tough fight tomorrow," Abdusattorov said.

Abdusattorov, the hero who won the World Rapid chess title as a 17-year-old lad two years ago, displayed the same grit and spunk that he showcased when he broke the record as the youngest ever title holder.

Mastering time management in rapid chess which uses faster time controls of 15 minutes plus three seconds increment, Abdusattorov found So resourceful enough in coming from a pawn down to win the first game in a tactical pair of a Ruy Lopez bishops and pawns endgame.

Abdusattorov equalized in the second game with the white side of a Queen's Gambit declined opening after So blundered early enabling him to set up a rook sacrifice in exchange for an unstoppable queening pawn in the endgame.

"I just need to sleep well, not be stressed and hopefully we can make a comeback tomorrow," said the 30-year-old So, who was born in Cavite before transferring to the US chess federation.

In the other semifinals match, Italian-American Caruana just could not nail down Carlsen, who likewise came from the brink of defeat in the opening game and still won. Caruana later equalized in Game Two and managed to tie, 2-2, on two wins and two losses to force a sudden-death armageddon.