Frederik Andersen made 27 saves for Toronto (3-1-0) in first of 10 meetings between the North Division rivals in the abbreviated 2020-2021 season. Marner added his second of the night into an empty net with 22.6 seconds left.
Kyle Connor replied for Winnipeg (1-1-0), which got 35 stops from Connor Hellebuyck inside an empty Scotiabank Arena because of COVID-19 protocols.
The Jets were minus sniper Patrik Laine, who sat out with an upper-body injury and is listed as day-to-day.
Following an even first period that saw both teams force good saves from Hellebuyck and Andersen, the ice tilted heavily in Toronto’s favour in the second.
The Leafs got the game’s first goal at 5:28 at the tail end of a power play when Hellebuyck kicked Jake Muzzin’s point shot out to William Nylander, who quickly fed Tavares in the slot for him to bury his third of the season with the Jets goalie out of position.
Toronto, which dressed 11 forwards and seven defencemen, led 13-0 on the shot clock after that goal, and 19-1 midway through the period with the Jets appearing to be asleep at the switch. Winnipeg looked to get some momentum on a man advantage of its own later in the period, but Hellebuyck was forced to stop two short-handed chances off the stick of Ilya Mikheyev.
The Leafs were finally rewarded a second time with 1:21 left when Auston Matthews carried the puck into the offensive zone before finding Justin Holl. His one-timer hit the post behind Hellebucyk, and Marner was there to poke home his second of the year.
Toronto appeared primed to take a feel-good 2-0 lead into the intermission, but got running around in the defensive zone following a Muzzin giveaway, with Connor providing Winnipeg some life by snapping his second past Andersen with under a minute remaining on the clock.
The Leafs finished the period with a 22-5 edge in shots and 36-11 in attempts directed towards goal, but only led by the slimmest of margins on the scoreboard.
Winnipeg got an early third-period power play after Muzzin took a holding penalty, but Andersen was there at every turn _ including a great stop on Mark Scheifele that would have had the fans inside Scotiabank Arena chanting “Freddie! Freddie!” in a normal season.
The Jets continued to make their push as the period wore on, and got a power play with 5:15 left in regulation when Toronto defenceman Morgan Rielly cleared the puck over the glass for a delay-of-game infraction, but Andersen and the penalty killers did the job as the home side held on before Marner bagged the empty netter.
The Leafs rebounded from Friday’s disappointing 5-3 loss to the Senators in Ottawa with a 3-2 victory in the rematch on the same ice 24 hours later, while Winnipeg opened its season with Thursday’s 4-3 overtime victory at home against the Calgary Flames.
Next up for the Jets are three straight games against Ottawa — Tuesday and Thursday in the nation’s capital before the teams travel to Winnipeg for a Saturday tilt — as part of a gruelling stretch of six contests in nine nights that began Monday.
The Leafs host the Edmonton Oilers on Wednesday and Friday before embarking on a four-game road trip through Alberta beginning Sunday.
Toronto announced before the game rookie winger Nick Robertson will miss at least four weeks with a knee injury, which forced the team to put both third-string goalie Aaron Dell and veteran forward Jason Spezza on waivers for salary cap purposes. Dell was claimed by the New Jersey Devils on Monday, while Spezza made it through and dressed against Winnipeg.
Notes: Mikko Lehtonen, who led all KHL defencemen in scoring last season, made his NHL debut for Toronto… Jets blue-liner Logan Stanley made his NHL debut for Winnipeg with Tucker Poolman still on the league’s COVID-19 list.