Kelly cut it to 3-2 at 6:53 with a tip-in of Erik Brannstrom's point shot for his first goal since Nov. 13.
Ottawa had a chance to tie the game on a 5-on-3 for 1:14 in the third period but Stutzle hit the post, and Bortuzzo blocked a shot.
"Everybody played desperate, especially, I want to mention Robert Bortuzzo," Tarasenko said. "It's unreal when you see a guy try to block a shot with every part of his body. It's a huge credit to those guys. They might not share some spotlights in the media, but inside the team, we know. It's insane, and it makes us proud of our teammates and makes us work hard."
Oskar Sundqvist made it 4-2 at 10:00 before falling over Murray in the crease. The goalie left the game 49 seconds later.
Tarasenko scored into an empty net at 17:49 for the 5-2 final.
"I think it's good for us to play a team like that to see what it takes," Senators defenseman Josh Brown said. "They're a good team, so yeah, it's a bit of a reality check. It's great to play teams like that. I think that's the next step for us as a younger group. We get to see how playing down low, cycling, and just hitting guys all over the ice, how that really pays off."
NOTES:Smith did not have an update on Murray after the game. … Schenn has scored eight points (four goals, four assists) during a five-game point streak. … Blues general manager Doug Armstrong got his 500th win as an NHL GM. … Ottawa forward Zach Sanford had one hit and one blocked shot in 15:26 of ice time in his first game against his former team. Sanford scored 71 points (36 goals, 35 assists) in 183 games for St. Louis and won the 2019 Stanley Cup. … The Senators were without forwards Josh Norris (shoulder), Drake Batherson (ankle), Colin White (shoulder) and Shane Pinto (upper body), and defenseman Thomas Chabot (undisclosed). … Senators forward Clark Bishop had an assist on Kelly's goal for his first point of the season in nine games. … Blues defenseman Justin Faulk had an assist to extend his point streak to four games (one goal, three assists).