Thomas won it when Philip Broberg’s shot from the point bounced off the crossbar behind goalie Alex Nedeljkovic, off Thomas’ skate and in.
Jimmy Snuggerud had a goal and an assist for the Blues (24-29-9), who traded captain Brayden Schenn to the New York Islanders and defenseman Justin Faulk to the Detroit Red Wings before the NHL Trade Deadline on Friday. Jordan Binnington made 23 saves.
Macklin Celebrini and Kiefer Sherwood each scored for the second straight game for the Sharks (30-25-5), whose three-game winning streak ended. Nedeljkovic made 11 saves.
Sherwood tied the game 2-2 at 13:26 of the third period. Philipp Kurashev had the puck behind the net and sent a pass to the left of the goal, and Sherwood’s one-timer beat Binnington through his blocker.
Snuggerud put the Blues up 1-0 at 6:55 of the first period. Cam Fowler passed to the left slot, and Snuggerud’s spinning wrist shot beat Nedeljkovic through the five-hole.
Celebrini tied the game 1-1 at 14:31 of the second period. Celebrini took the puck on the right wing from Dmitry Orlov and fired a wrist shot that beat Binnington’s blocker.
Thomas gave the Blues a 2-1 lead at 17:46. Snuggerud fed a pass from the left of the net to Thomas in the slot, and his one-timer beat Nedeljkovic by the blocker.
