Frazer McLaren needed eight stitches to close the cut on his chin from a fight, another four for a gash on his cheek carved open by a stick later in the game.
Still, it was McLaren who delivered the most damaging blow of the night.
Only 26 seconds into the latest installment of the Battle of Ontario, the Toronto tough guy decked Dave Dziurzynski when he caught the Ottawa forward flush with a right to the chin, sending him face down to the ice in a frightening scene.
''It was just a lucky punch. It happens sometimes,'' McLaren said.
A woozy Dziurzynski was slow getting up and eventually needed help from two teammates to skate off.
''Those are big, tough men fighting,'' Maple Leafs coach Randy Carlyle said. ''You see that, you just wish the trainer gets there quicker.''
Dziurzynski did not return, and the Senators said he had a concussion. He logged a total of 3 seconds in his 10th NHL game.
''I hope he's OK,'' said McLaren, who noted the Maple Leafs had a flat start last time out. ''I was just trying to get us going early. I asked him (to fight) and he actually said no, so I thought we weren't going to go and then he ended up dropping his stuff there when the puck dropped.
''He's a big guy and he actually gave me a few good ones early there.''
Senators center Zack Smith said he had checked on his teammate after the game and ''he looked fine.''
''That's what McLaren does and it was definitely good for Dziurzynski to step up, but I don't know if that was the best trade-off,'' Smith said. ''He's a big guy but it's just unfortunate he put himself in that situation.''
Toronto moved two points ahead of the Senators for fifth place in the Eastern Conference halfway through the season, shortened to 48 games by the NHL lockout. The teams entered tied for third in the Northeast Division.
''To me it's all irrelevant right now,'' Carlyle said. ''We've got a lot of work ahead of us.''
Mika Zibanejad, Smith, Daniel Alfredsson and Colin Greening had the goals for Ottawa, which lost its fourth in a row and dropped to 3-7-2 on road. The Senators are 9-1-2 at home.
From that point on, the teams stuck to hockey in a sloppy, wide-open game.
''We won the hockey game and got two points,'' Carlyle said. ''Is it a masterpiece? You be the judge.''
Toronto had trouble putting away the Senators and found itself under pressure late after Alfredsson made it 5-3. Greening stuffed in the puck to make it 5-4 at 18:03 of the third period with Ottawa goalie Ben Bishop on the bench.
As usual, Stompin' Tom Connors' ''The Hockey Song'' was played midway through the third. It made for a sad interlude this time, given news during the game that the Canadian music icon had passed away at 77.
''Stompin' Tom, you'll be missed. Thanks for all the memories and the greatest hockey song ever,'' public address announcer Andy Frost said during the song.
Wracked by injuries, the Senators have relied on some stingy defense. They came into the game ranked second behind Chicago in goals against, giving up just 1.83 per game.
The game marked the return of Senators wings Milan Michalek (knee) and Mark Stone (broken finger), who was making his regular-season debut.
Toronto led 2-0 after the first period despite being outshot 14-10. But the Maple Leafs were more dangerous, and goalie James Reimer was up to the task when Ottawa threatened.
Reimer has won six straight.
The Maple Leafs added to the lead at 1:20 of the second after Bozak outworked a Senators player behind the net, allowing Kessel to send the puck out in front where van Riemsdyk drove it home for his 13th of the season.
Ottawa quickly replied on a delayed penalty, with Zibanejad banging home a rebound from in-close at 2:48 for his fifth goal, cutting the lead to 3-1.
Smith cut the deficit to 3-2 at 1:40 of the third period. Left alone in front of the net, he poked in a rebound of Chris Phillips' shot from the point for his first of the season.
Kessel restored a two-goal lead at 3:42 with a low wrist shot from the circle on the power play for his sixth of the season. After being shut out in the first 11 home games this season, he has scored in two straight.
Kadri made it 5-2 when Bishop failed to control his shot at 10:18. It was Kadri's 10th of the season and fifth in three games.
An unmarked Alfredsson had time to measure his shot and beat Reimer for his fifth of the season at 12:08.
''At the end of the night I thought we were very competitive here on the road and we have to continue to push ourselves to continue to be better,'' Ottawa coach Paul MacLean said.
NOTES: Toronto forward Matt Frattin (knee) took part in the morning skate but did not play. ... The clubs split their two previous meetings this season, with the home team winning each time. ... The Maple Leafs entered with 22 fighting majors this season, one behind NHL-leading Columbus. ... Orr's 108 penalty minutes against Ottawa are his most against any team.