Columbus in 2009 traded goalie Pascal Leclaire and a second-round pick in the NHL Draft to Ottawa for forward Antoine Vermette.
Ottawa used that 46th selection on Lehner, and Tuesday in Nationwide Arena he played against the Blue Jackets for the first time, with starter Craig Anderson out with a neck injury suffered in overtime Sunday against the Dallas Stars.
Lehner made 32 saves in Ottawa's 4-1 win that ended a five-game winless streak. It was his first victory in five starts (1-2-2) this season.
"It feels great," Lehner said. "It was one of our better games this year, not too many breakdowns."
Problems continue for Columbus (5-9-0), losers of four straight and 3-5-0 at home.
"We definitely did some good things," Columbus forward Jared Boll said. "We're not getting the bounces. We're not getting enough goals. We can't wait until the third period to give your last-ditch effort to try and play catch-up.
"It's been a tough little stretch here. We have to keep it together in the room."
The Blue Jackets have scored three goals total in the past three games and faced a backup goaltender for the second straight time after Jeff Zatkoff of the Pittsburgh Penguins made 19 saves to shut them out, 3-0, for his first NHL win.
"At times we try to get too cute with the puck," Columbus coach Todd Richards said. "We've had opportunities to get pucks to the net, but we had a lot of shots blocked. … When you're full of confidence, you score."
Columbus could not solve Lehner until Umberger's goal at 3:02 of the third period made it 2-1. Umberger was being checked by Marc Methot in the low slot when he picked the puck off the stick of Chris Phillips. Umberger then took the shot from his knees for his second goal.
"I was like, 'Here we go again' but right after that we took over the game again," Lehner said. "We kept up on grinding. They weren't in our zone for a while."
Chris Neil iced the win for the Senators at 13:55 by taking a pass from Jason Spezza and beating Curtis McElhinney. Neil 29 seconds later dropped the gloves with Dalton Prout for his second fight of the period after earlier engaging Jared Boll. Those were among four fights.
"It was a high-intensity game," Neil said. "Both teams were desperate and that's what comes with it."
Karlsson scored his sixth goal of the season into an empty net with 18 seconds left.
"We played a real solid 60 minutes," Ottawa coach Paul MacLean said. "We handled the momentum swings better. I thought our penalty killers were outstanding.
"Right after they did score we had some good shifts. We handled that momentum swing better than any in the game."
Ottawa took the lead with two rushes that resulted in goals after spending most of the first period defending. Columbus had eight of its 13 shots, plus another off the crossbar by James Wisniewski, during two power plays, but Lehner was unyielding, particularly on the first kill when he made six saves.
A minute after the Senators returned to full strength, Karlsson struck on their eighth shot. He created a turnover in the neutral zone then skated to the right dot, where he snapped a wrist shot under the crossbar to fool McElhinney at 14:51 for the unassisted goal.
Another transitional goal came with 3.9 seconds left when the Blue Jackets' defensive-zone coverage fell apart. The Senators created an odd-man rush with Kyle Turris left alone in the slot for a one-timer he fired left of goal. As two Blue Jackets swiped at the rebound off the boards, Bobby Ryan swooped in, wheeled behind the net and fed MacArthur for the bang-bang goal.
McElhinney, who stopped 20 of 23 shots, made consecutive starts for the first time this season in place of Sergei Bobrovsky after making 24 saves in the loss to Pittsburgh. McElhinney's previous two starts came in the second of back-to-back games.
The game was the second of a four-game homestand for the Blue Jackets before they go on the road for seven of eight.
"You've got to work hard to create your own bounces, and I believe we have a gritty team that can make it happen," center Brandon Dubinsky said.