Denver started out strong, leading by as many as 14 points at several points, but Chicago kept pushing back, with the Bulls' starters outscoring the Nuggets' starters 104-48 mismatch.
"Tonight, we were forcing it, we just didn't play well defensively," Karl said. "I'm proud of the way we stayed strong especially at the end when we were down four and made the big shots. This was a difficult mental game because we let go of a lead in regulation where we should have won it."
The Nuggets' eight-point lead with 3:26 left in the fourth quarter evaporated, and Ty Lawson's last-second jumper fell short, sending the game into overtime.
On the flip side, Karl was heartened that Denver got 71 points from its bench, including Chandler's outstanding play.
"Anytime when we bring (Chandler) off the bench we seem to get an offensive spurt," Karl said. "I think he is our most efficient offensive person on the team. He also plays some good defense."
Denver outscored the Bulls 21-20 in the first quarter and 53-45 at the half, but Chicago came back to outscore the Nuggets 28-26 in the third quarter and 60-52 for the second half.
Even though his team's 12th consecutive win didn't come easy, Karl was happy to get out of Chicago with the win.
"Nine (wins) in a row in January and now with 12, we know we can win and play anyone," Karl said. "We're building confidence. However, we're just trying to get to a number like 54 or 55 wins. We believe there is value in every game. We're just doing a nice job coming together and building confidence."
NOTES: The only member of the Nuggets who was alive the last time Denver won 11 straight games is point guard Andre Miller, who was four days away from his seventh birthday on March 15, 1983. ... Denver plays its 14th back-to-back on Tuesday at Oklahoma City before returning home to face Philadelphia (Thursday) and Sacramento (Saturday). ... Chicago, meanwhile, continues its homestand Thursday against Portland Trail Blazers. . Denver leads the series with Chicago 44-37.