OTTAWA (AP) -- The Tampa Bay Lightning took advantage of Ottawa's struggles to keep their winning streak going and extend the Senators' skid.
Valteri Filpulla and Eric Brewer also scored for the Lightning, who have won five in a row. Ben Bishop stopped 27 shots.
Tampa, second in the Atlantic Division with 83 points and 11 games remaining, is peaking at the right time.
''We just seem to be scoring tons of goals,'' Bishop said after getting his 34th win of the season. ''We're rolling right now and we have a big game against Pittsburgh so hopefully we can keep it going.''
''What is there to say now, I don't know, it's pretty empty,'' Lehner said. ''It's tough to be in there right now. I can say again, yeah I sucked ... I'm trying to be there and trying to step up to make saves, but the players are so good in this league and they get too much time. It's tough.''
The Senators have talked about the need to play better and play smarter, but coach Paul MacLean said it's the same mistakes that keep coming back to plague his team time and time again.
''Groundhog day,'' MacLean said. ''Thirteen giveaways, six minor penalties, we played too much in our zone and ends up in the same thing.''
After Callahan put the Lightning up 5-3, Michalek deflected Karlsson's shot from inside the blue line with 2:53 to go.
Ottawa then had a great chance to tie it as Callahan took a penalty with 55 seconds remaining. However, with Lehner on the bench for an extra skater - giving the Senators a two-man advantage - they were unable to beat Bishop.
''We competed to the end, but once again we didn't find a way to win,'' Senators captain Jason Spezza said. ''We fought right to the end, but once again we found a way to lose.''
Brewer scored his first goal in 95 games to give the Lightning a 4-3 lead at 3:48 of the third with a great shot off his backhand to sneak the puck in under the crossbar.
''I've seen him do that a few times,'' said Bishop. ''He's good for a couple of those a year.''
The Lightning took a 3-2 lead at the five-minute mark of the second period on a power-play goal by Filpulla, who knocked home a rebound just out of Lehner's reach.
Hemsky tied it after displaying some great puck handling before beating Bishop late in the second. The goal earned him a standing ovation from the 17,136 on hand.
''It's a nice goal, but in the end it really doesn't matter if you lose,'' Hemsky said. ''The people reacted great.''
The Senators ended the first period tied 2-2 after getting off to a horrible start. Purcell, who hadn't scored in his last 19 games, ended his drought just 23 seconds into the game.
Ottawa managed to tie it on MacArthur's short-handed goal midway through the period. It was MacArthur's 21st of the season, tying a career high.
The Lightning regained the lead on Purcell's second of the night as he managed to dig the puck out through traffic in the crease and then shoot it in off the post.
Karlsson rounded out the scoring with a power-play goal, beating Bishop with a shot from just inside the blue-line.
NOTES: G Craig Anderson (upper body injury) and G Nathan Lawson (lower body injury) missed the game for Ottawa, and D Patrick Wiercioch and LW Matt Kassian were healthy scratches. ... The Lightning signed free-agent forward Cody Kunyk to a one year, two-way NHL contract. Kunyk, 23, skated in 37 games for University of Alaska-Fairbanks this season, posting 22 goals and 43 points. ... D Keith Aulie, D Mark Barberio, C Tom Pyatt and RW Nikita Kucherov were healthy scratches for Tampa Bay.