Yakemchuk, a 20-year-old defenseman, was the No. 7 pick in the 2024 NHL Draft.
Lars Eller also scored for the Senators (38-24-9), who have won four straight and are 15-3-2 in 20 games since Jan. 25. Linus Ullmark made 32 saves.
Ottawa moved into the second wild card into the Stanley Cup Playoffs from the Eastern Conference.
Multiple injuries to Ottawa defensemen, including Thomas Chabot (upper body) and Lassi Thomson (undisclosed) in a 2-1 win against the New York Rangers on Monday, meant Yakemchuk and Jorian Donovan, a fifth-round pick in the 2022 NHL Draft (No. 136), each made his NHL debut against Detroit.
Dylan Larkin scored in his return from a lower-body injury, and Dominik Shine also scored for the Red Wings (38-25-8), who have lost five of their past seven games (2-4-1). John Gibson made 18 saves.
Detroit fell one point behind both the Senators and New York Islanders.
The Red Wings appeared to take a 1-0 lead on Alex DeBrincat’s power-play goal at 15:35 of the first period, but the play was overturned after the Senators successfully challenged for offside.
Instead, Tkachuk’s power-play goal put the Senators ahead 1-0 at 17:15. As Gibson got into position to stop Tim Stutzle’s shot, Tkachuk tipped it past his blocker. Yakemchuk picked up the secondary assist for the first point of his NHL career.
Yakemchuk made it 2-0 at 9:28 of the second period with his first NHL goal, skating in from the blue line to beat Gibson with a wrist shot.
Eller then extended it to 3-0 at 11:05 with his fourth goal of the season.
Shine cut it to 3-1 at 14:50, tipping Simon Edvinsson’s pass between Ullmark’s blocker and body.
Larkin, playing for the first time since March 6, made it 3-2 with a power-play goal at 4:13 of the third period. Ullmark deflected Alex DeBrincat’s pass across the top of the crease, but the puck went right to Larkin for his 29th goal.
James van Riemsdyk hit the post with 4:22 to play and the Red Wings on a power play.
