Max Pacioretty's goal with 5:39 left lifted the Toronto Maple Leafs to a 4-2 series-clinching victory over the host Ottawa Senators in Game 6 of their Eastern Conference first-round matchup on Thursday.

The 36-year-old forward, who missed the last two months of the regular season and first two games of the postseason with an undisclosed injury, helped the Maple Leafs overcome giving away a 2-0 advantage with his game-winning goal and an assist. Toronto's William Nylander celebrated his 29th birthday with two goals and an assist, and Auston Matthews also scored.

"A lot of ups and downs mentally," Pacioretty told Sportsnet after the win. "Coach (Craig Berube) did a good job of kind of easing me into the series. Because, you know, given the role and my age, you can't just jump in and play a ton of minutes."

Goalie Anthony Stolarz stopped 21 shots for the Maple Leafs, who closed out the best-of-seven series and advanced to face the defending Stanley Cup champion Florida Panthers in the next round.

Brady Tkachuk and David Perron scored for Ottawa, with Thomas Chabot assisting on both. Linus Ullmark finished with 19 saves.

The loss ends Ottawa's first postseason run in eight years.

"I know it sucks right now, but I really can't wait for what the future holds," Tkachuk told reporters.

After being blanked 4-0 at home on Tuesday, the Maple Leafs came out as the aggressors on Thursday, and then they took the game back late to advance to the second round of the playoffs for just the third time since 2004.

Toronto jumped ahead thanks to a couple Senators mistakes. Tkachuk was called for interference with 1:59 left in the first period after hitting Brandon Carlo at center ice.

Matthews responded with a goal on a sliding shot from the point that found the narrow gap between the post and Ullmark's skate with 1:10 remaining in the opening period. Mitch Marner and Nylander got the assists.

Nylander doubled the lead in the opening minute of the second by taking advantage of a turnover Pacioretty caused on Nick Jensen at the blue line.

Tkachuk got one back for the Senators with 12:32 left in the second. Ottawa won the faceoff after an icing call against the Leafs. The Senators captain managed a midair tip of Chabot's shot from the left point that got past Stolarz.

Perron equalized on a goal that bounced in off Stolarz's back with 7:20 left in regulation. However, Toronto's oldest active player put his team back up less than two minutes later when the Senators failed to clear the puck after a Toronto two-on-one attack.

Nylander's empty-netter with 19 seconds left ensured the Maple Leafs' victory.

--Field Level Media