Lehner made 30 saves for Chicago (0-2-1), which scored shorthanded and on a power play.
"I felt good," Lehner said. "I felt like I saw the puck well, I thought rebound control was good. The first one is unfortunate, it squeaks through. But I was where I wanted to be in position and somehow it goes in, got to try to clean that up.
"And the third goal, it just dove on me. He missed his shot. It's unfortunate. But I thought I made some good saves and felt comfortable. We got a point, which is something, but should've got a win today."
Brandon Saad gave the Blackhawks a 1-0 lead at 4:02 of the first period with a shorthanded goal on a 2-on-1 with Ryan Carpenter.
"I think we did a good job in the first and they kind of took it to us in the second," Saad said. "[Lehner] made some big saves and the third was kind of even. But we definitely had chances to close it out and we didn't. At least we got a point and we have to move on from it."
Brent Seabrook extended the lead to 2-0 with a power-play goal at 12:37, scoring stick-side from the right face-off circle off a rebound.
Ehlers scored a power-play goal to make it 2-1 off a one-timer from the right circle at 7:05 of the second period after receiving a pass from Neal Pionk.
Andrew Copp tied it 2-2 at 11:44 of the third, scoring stick-side from in front off a pass from Kyle Connor.
"We were tapping each other, 'Let's go get another one right now,'" Copp said. "You don't want to be giving away points in the Central Division. I don't think we were playing for [overtime]. We were out there to win."