1st period
After what was a stalemate of a first period for most of the time, Ottawa Senators captain Brady Tkachuk committed an unnecessary roughing penalty that put the Maple Leafs on the power play with just 2:19 to go.
And, of course, the Maple Leafs take advantage after captain Auston Matthews put one in the net for his second goal of the series just over a minute into the power play.
Toronto finished the period with seven shots on goal to Ottawa's three, also outhitting the Senators 27-18.
Ottawa had a chance to score but failed on a two-versus-one breakaway opportunity in which Toronto goaltender Anthony Stolarz made a save.
2nd Period
Toronto wasted zero time getting on the board again after William Nylander put the Maple Leafs up 2-0 with a goal just 43 seconds into the period.
But Tkachuk redeemed himself this time around after getting a piece of the puck that got past Stolarz with an insane redirect to the top left corner of the net. This marked his fourth goal of the series which was followed by all the fans chanting his name.
But after the two goals early on, things died down quite a bit with neither team committing any penalties but both goaltenders making a handful of clutch saves to keep both of their teams in the game.
The Senators played much more physical than the Maple Leafs this period, outhitting them 26-9. But both teams were almost dead even in shots on goal (TOR-9, OTT-8), leading Ottawa into the intermission with momentum.
3rd Period
After failing on an earlier power play, the Senators came back and tied it up after David Perron scored his second goal of the season after shooting the puck off of Stolarz's back to send the Ottawa fans into a frenzy with 7:20 left to go.
But just 81 seconds after Ottawa tied it up, Max Pacioretty scored his first goal of the series to give the Maple Leafs a 3-2 lead with just five minutes left to go.
Then, just when the Senators tried all they could to muster up a chance to tie the game, Nylander scored the empty-net goal, despite being tripped, to end the game with a score of 4-2.
The Leafs will now advance to the second round to face the Florida Panthers.