OTTAWA - The Toronto Maple Leafs fought hard through the last 40 minutes of Wednesday's game. But it was the first 20 that did them in.

The Ottawa Senators scored three times in the first period and held on for a 4-3 win to send the Maple Leafs to the all-star break on a six-game losing streak.

"I scratch my head when I talk about that first period again," said Toronto's interim head coach Peter Horachek. "That was totally done by ourselves, to ourselves, to a team that played (Tuesday) night.

"We wanted to play more like we played in the second and third period and come out with some energy and put more pucks to the net and create more chances, but it's a strange situation so we've got to correct that for sure."

Toronto is now 1-7 under Horachek and has just three wins in its last 17 games.

Erik Karlsson scored twice to lead the Senators (19-18-9), who were coming off a 3-2 overtime loss in New York on Tuesday night, while Mike Hoffman and Mika Zibanejad also scored. Craig Anderson stopped 37 shots.

Nazem Kadri, David Clarkson and James van Riemsdyk replied for the Leafs (22-23-3). James Reimer made 22 saves and lost for just the second time in his career at Canadian Tire Centre (8-2-0).

"We just have to keep trying to move forward," said Kadri. "That's really all we can do is try and stay positive and we just have to play with that desperation through 60 minutes instead of 40 or 45."

Added Reimer: "We didn't have a good start. Obviously you can't get down 3-0 and then expect to win in this league. I thought we did a great job of battling back and working hard in the last 40 minutes, but just ended up falling a bit short."

Toronto made things interesting for the 18,894 on hand as Kadri scored a power-play goal at 2:36 of the third period. Kadri took a pass from Morgan Rielly and beat a screened Anderson to make it 3-2.

The Leafs did their best to score the equalizer, but were unable to create any real solid scoring chances, and with less than five minutes remaining in regulation, Karlsson scored his second of the night to make it 4-2. Milan Michalek grabbed the puck behind the net and found Karlsson just inside the blue-line and he beat Reimer glove side.

Van Riemsdyk scored at 18:37 to again pull Toronto to within a goal, but that's the closest the Leafs would get.

"It was a big win for us," said Anderson. "We make sure the fans get everything they pay for when we make it close at the end."

"I had confidence in the guys that we were going to get the job done," added Anderson. "We made sure that we got the puck out of our zone to end the game and that's huge for us to get some confidence heading into the break. We can come back hopefully feeling good about ourselves and we can continue to play well."

The Maple Leafs had a better second period but were only able to beat Anderson once. Clarkson, with just his second goal in 20 games, got the Leafs on the board at the 13-minute mark of the period.

The Senators nearly regained the three-goal lead late in the period, but Reimer was able to stop a 2-on-1 to keep the Leafs within reach.

Toronto had an opportunity to score in the opening minutes of the game as Phil Kessel had a breakaway, but shot wide of the net. Less than a minute later Mark Stone, who extended his point streak to seven games with an assist (2G, 6A), fed Hoffman at centre ice and he beat Reimer with a shot under the crossbar.

Midway through the first period, Karlsson scored his 10th goal of the season following a great give-and-go with Hoffman.

The Senators capped the period scoring on a delayed penalty call as Bobby Ryan found Zibanejad all alone.

"We came out strong and definitely got the advantage right off the hop," said Hoffman. "We knew they were going to come back and make a strong push. They got a few, we got a few and our goalie played well.

"At the end of the day (we) just stuck with it and played for 60 minutes and came out with the two points."

Notes: D Chris Phillips, C Colin Greening and C David Legwand were healthy scratches. C Zack Smith (wrist) and D Mark Borowiecki (leg) remain sidelined for the Senators. Toronto D Stephane Robidas and D Korbinian Holzer were healthy scratches, while Leo Komarov remains sidelined with a lower body injury.