Celebrini scored twice in the second period.
The first pick in the 2024 NHL Draft made it 2-1 at 5:43 off a 2-on-1, finishing his own shot after a block by Blues defenseman Colton Parayko on his initial attempt.
"That was a lucky bounce," Celebrini said.
Celebrini's power-play goal at 19:53 made it 3-1, a shot from the left circle after the Blues failed to clear the puck multiple times.
"It was a great keep by [Walman], great pass by [Mikael Granlund]," Celebrini said. "I just felt like I could put one on net and see what happens."
Schenn cut it to 3-2 at 5:34 of the third period, finishing off a loose puck to the right of the net, but Walman made it 4-2 at 6:01, scoring into an open net off a 2-on-1 with Kovalenko.
Kyrou cut it to 4-3 at 7:57 off a close-range chance at the left side of the crease.
"We wanted to start on time, we didn't start on time," Blues coach Jim Montgomery said. "We didn't manage the game well enough early on, and even after we score to make it 3-2 and we have all the momentum, we give up another odd-man rush. Very similar to the second goal that they got. We made too may mistakes and had to fight too hard to get back into the game too many times."
NOTES: Celebrini has seven points (three goals, four assists) in three games against St. Louis; he has 12 points (seven goals, five assists) in 17 games against the rest of the League. ... With 19 points (10 goals, nine assists) through 20 games this season, Celebrini became the 11th 18-year-old in NHL history to record as many points through their first 20 career games and just the fourth in the past 30 years, following Sidney Crosby (24 points; nine goals, 15 assists), Patrick Kane (22 points; seven goals, 15 assists), and Ryan Nugent-Hopkins (20 points; eight goals, 12 assists). ... The Sharks were outscored 14-4 during their three-game losing streak. ... San Jose defenseman Shakir Mukhamadullin played 15:40 in his season debut and fourth NHL game. ... Blues center Robert Thomas had an assist to give him 10 points (three goals, seven assists) in a five-game point streak and 14 points (four goals, 10 assists) in 11 games after returning from a fractured right ankle. ... St. Louis forward Pavel Buchnevich had an assist to give him seven points (two goals, five assists) his past seven games and 19 points (four goals, 15 assists) in 17 games against San Jose.