Giroux, who also had an assist, signed a three-year, $19.5 million ($6.5 million average annual value) contract with Ottawa on July 13.
Alex DeBrincat and Shane Pinto also had a goal and an assist each, and Mathieu Joseph had two assists for the Senators. Anton Forsberg made 21 saves.
Nick Suzuki had two assists in his preseason debut, and Sam Montembeault made 18 saves for the Canadiens, who have lost their first six preseason games (0-5-1).
DeBrincat gave Ottawa a 1-0 lead at 3:13 of the first period on the power play, Giroux’s time for his third goal of the preseason.
Giroux extended it to 2-0 at 5:52 of the second period, with a pass from DeBrincat.
Joel Armia made it 2-1 at 8:20, and David Savard scored 44 seconds later at 9:04 to tie the game at 2-2.
Tyler Motte scored his third goal of the preseason to give the Senators a 3-2 lead at 11:10, and Pinto restored a two-goal lead for the Senators with his fourth preseason goal at 18:53.
Cole Caufield made it 4-3 on the power play at 14:57 of the third period, but Brady Tkachuk scored his first goal of the preseason 1:11 later at 16:08 to give Ottawa a 5-3
Arber Xhekaj had his shot on the wrist of Joseph’s hand at 16:36 to make it 5-4.
Blues 4, Wilds 2: Pavel Buchnevich had a goal and an assist for the St. Louis Blues in a 4-2 win over the Minnesota Wild at the Enterprise Center in St. Louis.
Jordan Binnington stopped all 11 shots he faced in the first two periods for the Blues. Joel Hofer made 15 saves in relief.
Tyson Jost and Mason Shaw each had a goal and an assist for the Wild. Filip Gustavsson made 23 saves.
Buchnevich scored on a layup from the right circle at 1:05 of the first period to give St. Louis a 1-0 lead.
Jake Neighbors’ power play goal from the left circle made it 2-0 at 11:42.
Nathan Walker scored from the slot to make it 3-0 at 10:18 of the second period.
Shaw made it 3-1 on a rebound at 6:58 of the third period, but Klim Kostin scored at 13:57 for the Blues to take a 4-1 lead.
Jost scored at 19:19 to make it 4-2.
Islanders 4, Flyers 3 (OT): Noah Dobson scored with eight seconds left in overtime to give the New York Islanders a 4-3 victory against the Philadelphia Flyers at the Wells Fargo Center in Philadelphia.
Josh Bailey had a goal and two assists, and Adam Pelech had two assists for the Islanders, who agreed to an eight-year deal with center Mathew Barzal earlier Tuesday. Ilya Sorokin made 30 saves.
Scott Laughton had a goal and an assist, and Samuel Ersson saved all 15 shots he faced in 29:17 for the Flyers (1-4-1) in their final preseason game. Troy Grosenick made 14 saves in relief.
Laughton scored on a short break at 2:09 of the second period to give Philadelphia a 1-0 lead.
Bailey tied it 1-1 with a power-play goal at 16:13, and Casey Cizikas scored shorthanded at 18:22 to make it 2-1.
Owen Tippett scored at 5:05 of the third period to tie it 2-2, and Tanner Laczynski put the Flyers ahead 3-2 at 8:53.
Anders Lee tied the game at 3-3 for the Islanders at 12:19.
Video: Dobson scores in OT to lift Islanders to 4-3 win
Sabers 4, Hurricanes 2: Tage Thompson and Dylan Cozens each had a goal and an assist for the Buffalo Sabers in a 4-2 win over the Carolina Hurricanes at the KeyBank Center in Buffalo.
Vinnie Hinostroza and JJ Peterka scored, and Craig Anderson made 23 saves for Buffalo.
Jamieson Rees and Malte Stromwall scored, and Pyotr Kochetkov made 26 saves for Carolina (4-1-0) in its preseason finale.
The Sabers took a 3-0 lead after the first period.
Hinostroza made it 1-0 at 6:59 on Buffalo’s 10th straight shot to start the game.
Thompson skated around Hurricanes defenseman Ethan Bear and scored over Kochetkov’s shoulder to make it 2-0 at 10:52.
Cozens took a 3-0 lead at 18:16 when he intercepted a drop pass in his own zone and scored on a short breakaway.
Rees made it 3-1 at 1:45 of the third period, and Stromwall scored 19 seconds later at 2:04 to pull Carolina within 3-2 before Peterka scored into an empty net at 18:40 for the final 4-2. .
Sabers forward Kyle Okposo suffered an upper-body injury in the second period and is not expected to be out for a few days, according to coach Don Granato.
Hurricanes defenseman Dylan Coghlan left the game in the first period with a lower-body injury.
Video: Thompson, Cozens help Sabers beat Hurricanes 4-2
Sharks 3, Eisbaren Berlin 1: Steven Lorentz scored the go-ahead goal for the San Jose Sharks in a 3-1 win against Eisbaren Berlin in the NHL Global Series Challenge at the Mercedes-Benz Arena in Berlin.
Tomas Hert scored for the Sharks, and James Reimer made nine saves in 31:25. He was replaced by Kaapo Kahkonen, who made nine saves.
Giovanni Fiore scored and Tobias Ancicka stopped all 21 shots Eisbaren faced at 30:01 before being replaced by Juho Markkanen, who allowed three goals on 15 shots.
Fiore gave Eisbaren a 1-0 lead at 12:10 of the second period with a shot from outside the left circle.
Hertl tied the game 1-1 at 17:06 of the second period after a challenge on Timo Meier, scoring in front of the net. Lorentz gave the Sharks a 2-1 lead by scoring 40 seconds later at 17:46, off a shot by Erik Karlsson.
Luke Kunin made it 3-1 with a shorthanded goal at 11:56 of the third period.
The Sharks open the regular season against the Nashville Predators in Prague on Friday and Saturday as part of the 2022 NHL Global Series (2 p.m. ET; NHLN, NBCSCA, BSSO).
Video: Hertl, Sharks beat Eisbaren in Global Series Challenge
Ducks 5, Kings 4: Derek Grant had a goal and three assists for the Anaheim Ducks in a 5-4 win against the Los Angeles Kings at the Honda Center in Anaheim.
Max Jones scored twice, Pavol Regenda had a goal and two assists, and John Klingberg had two assists for the Ducks. Anthony Stolarz made 32 saves
Gabriel Vilardi had two goals, and Cal Petersen made 27 saves for the Kings.
Vilardi gave Los Angeles a 1-0 lead at 11:06 of the first period on the power play, scoring a rebound.
Grant tied the score at 1-1 at 13:56 when his shot deflected off Kings defenseman Jordan Spence’s post.
Vilardi scored his second goal at 2:16 of the second period to give Los Angeles a 2-1 lead, and Arthur Kaliyev scored 33 seconds later on a quick shot from the right circle at 2:49 to extend – it to 3-1.
Jones made it 3-2 at 4:09 after his slap shot went in past Kings forward Carl Grundstrom. Tobias Bjornfot restored a two-goal lead for Los Angeles at 7:47 from the left circle.
Jones scored his second goal off a no-look backhand pass between the legs of Grant to cut it to 4-3 at 14:44.
Regenda tied it 4-4 at 16:48 with his third goal of the preseason. Frank Vatrano scored 51 seconds into the third period on the power play for a 5-4 final.
Video: Jones scores 2 goals in 5-4 win over Kings
Golden Knights 4, Coyotes 3: Adin Hill made 50 saves for the Vegas Golden Knights in a 4-3 win against the Arizona Coyotes at T-Mobile Arena in Las Vegas.
Arizona outscored Vegas 53-28, including 28-5 in the second period when Hill made 26 saves.
William Karlsson gave the Golden Knights a 4-3 lead from the right circle at 18:02 of the third period.
Zachary Hayes scored twice and Michael Amadio had three assists for Vegas.
Barrett Hayton had a goal and two assists, and Jonas Johansson made 24 saves for Arizona.
Hayes gave the Golden Knights a 1-0 lead at 8:53 of the first period and made it 2-0 at 13:57, each with an assist from Amadio.
Matias Maccelli made it 2-1 at 4:19 of the second period on a rebound off the right post before Hayton tied it 2-2 at 6:01 when the puck deflected off his skate on the rebound of a shot by Dylan Guenther. .
Pavel Dorofeyev gave the Golden Knights a 3-2 lead, scoring from the slot off a pass from Sakari Manninen at 12:06 of the third. Alex Chiasson tied it 3-3 on the power-play at 17:44 with the Coyotes playing 6-on-4 after Johansson was taken out.
Video: Karlsson drives Golden Knights to win with goal