Ice-time for Dion Phaneuf who also had four blocked shots and one hit.
Leafs' penalty killing on the season after allowing two goals on four chances.
Leafs' record in the second game of a back-to-back this season.
``When you're a young hockey club, if you can play five-on-five even up and win your specialty teams battles, you're going to win most nights. This was a big game and they're playing great hockey right now and we knew it was a big challenge.''
Lehner made his first start of the year after being called up from Binghamton of the American Hockey League earlier in the weekend and made 23 saves.
The loss snapped a two-game winning streak for the Leafs, but they closed out a respectable first month of the season. The big thing for coach Ron Wilson is that his club still has not lost two games in a row.
``Our attitude is not to lose two games in a row and what's happened has happened. We're focused on the next game because we didn't accomplish anything other than have a fairly good month,'' Wilson said.
"It's hard to tell what happened. It could have been ramped a little bit or fluttered on him. You can't really tell. I haven't talked to him. But you know the first goal against that they scored we got caught napping and I think that had a big impact on the game because I thought at that point we had a 1-0 lead and we were in pretty good control and we had our forecheck going. You know a team like Ottawa, no different than us if they can get a goal like that it kind of lights the candle and it did for them. They played pretty well after that until the last 10 minutes of the game."
``We have to focus for our next two games which are on the road and go from there.''
The Senators beat the Maple Leafs for the first time this season following a 6-5 loss in Toronto earlier this year.
Heading into the third period with a 2-1 lead, Senators forward Zach Smith stole the puck from Matthew Lombardi just inside the Leafs line and dished it off to Daugavins, who scored with a long shot that beat Gustavsson at 7:08.
MacArthur responded less than two minutes later to pull the Leafs to within a goal. Shortly after the Leafs went on a power play as Daugavins was called for hooking, but they failed on that opportunity and couldn't beat Lehner the rest of the way.
``The game went pretty fast up and down the rink and I thought at the end of the game we defended way more than I would have liked,'' said Senators coach Paul Maclean.
``We defended well enough to win the game obviously but we played most of the third period, especially after we got the lead, in our own end. I thought Robin Lehner made a couple of saves that were big.''
MacArthur opened the scoring 11 minutes into the first period as Senators defenceman Erik Karlsson sat in the penalty box for slashing.
Greening tied the game a little less than five minutes later on the power play, as the first period ended in a 1-1 tie.
Neil tipped a point shot from Karlsson past Gustavsson, again on the power play, for the only goal of the second period.
Notes: Senators forward Jason Spezza had his six game point-scoring streak snapped Sunday. He had 11 points over the previous six games...Senators defenceman Erik Karlsson leads the NHL with 12 assists...Senators forwards Zenon Konopka and Chris Neil are first and second respectively in the NHL with 49 and 46 penalty minutes...Phil Kessel had his four-game point streak halted Sunday, but he still leads the Leafs and the NHL with 18 points in 11 games.
Wednesday, November 2
@ New Jersey Devils
7:30 PM ET (TSN, AM640)
The Leafs are on the road once again playing the first game of a back-to-back against the New Jersey Devils for the first of four meetings this season. After playing in New Jersey Wednesday, the Leafs are in Columbus Thursday.
This will be the Devils' first game after a four-game road trip that saw them lose three games.
1 - 0 TOR
1 - 1 Tie
2 - 1 OTT
3 - 1 OTT
3 - 2 OTT
Illegal check to head