Mitch Marner had the shootout winner to lead the Maple Leafs past the Vegas Golden Knights 4-3 after Toronto blew a two-goal lead.
Nazem Kadri had a pair of goals in regulation time for Toronto (9-7) and James van Riemsdyk also scored as the Maple Leafs built a 3-1 lead by the first intermission.
Frederik Andersen made 22 saves and stopped three players in the shootout.
Deryk Engelland's third-period goal forced overtime for Vegas (9-5), while James Neal and Reilly Smith also scored. Lagace turned aside 25 shots.
The win was a much-needed boost for a Maple Leafs team that had dropped back-to-back games and lost six of their past 10 after starting the year with a 7-1 record.