At 40-10, the Bulls clinched a playoff spot.
Teammate C.J. Watson drove for the basket but his shot was partially blocked by Toronto's James Johnson and Deng was there for the winner. After officials reviewed the play to make sure Deng's shot beat the buzzer, the Bulls had a 102-101 overtime victory on a night in which they were often outplayed by the 16-win Raptors.
"We're lucky we had enough time to get the rebound," Deng said. "When it left my hand it felt good because I saw the light after it left my hand. But then again, you never really know. We waited until they made the decision."
Johnson, an ex-Bull, had 20 points, eight rebounds and four blocked shots, part of another determined effort by the Raptors, who gave Chicago a scare three nights ago before losing.
"That's what happens sometimes," Johnson said.
"The ball happened to fall short after I blocked it and Luol Deng made a great play. We deserved to win tonight, but they made the game-winning play."
Carlos Boozer had 24 points and 10 rebounds for the Bulls, Deng added 23 points and 10 rebounds, and Watson had 23 points.
Jose Calderon also had 20 points and 10 assists, and Gary Forbes had 12 points and 13 rebounds for the Raptors, but missed two free throws with 6.4 seconds left in overtime.
Chicago coach Tom Thibodeau was anything but pleased after the victory. The Bulls had beaten the Raptors 94-82 on Wednesday night in Toronto after trailing by 12 in the second half.
"We hung in but the disappointing thing is that it's two games in a row," Thibodeau said. "We found a way to win. ... Very fortunate. We were lucky to get that game. They outplayed us from the start. They dominated us. They outrebounded us by 14."
The Raptors had a 58-44 rebounding edge, were aided by Chicago's horrendous 3-point shooting — 3-for-23 — but were hurt by 20 turnovers.
"You block the shot, there was a scramble. They had nothing going, they get the loose ball and put it in. That's the microcosm of the season," Toronto coach Dwane Casey said.
The Bulls were already without star guard Derrick Rose, who sat out his sixth straight game with a groin injury. And then they lost centre Joakim Noah, when he was ejected with 1:28 left in the opening half after picking up two technical fouls.
After he was called for a personal foul under the basket, Noah apparently got one technical for complaining and then a second after throwing the ball in the direction of an official.
"We are short-handed already. We can't have that," Thibodeau said.
The Raptors also were thin and used only eight players after beating the Knicks on Friday night. DeMar DeRozan missed the game with an ankle injury and Jerryd Bayless was out with a hip pointer.
Calderon hit a go-ahead jumper for Toronto in the extra period before Boozer hit two free throws with 1:19 left for another tie at 100.
Johnson, was fouled with 15.2 seconds to go and hit the second of two free throws to give the Raptors a 101-100 lead.
With the game tied at 94, the Raptors got off three shots in the closing seconds of regulation and after a wild scramble, the ball was knocked out of bounds and Toronto maintained possession with 3.9 seconds left following a video review.
Andrea Bargnani then had a good look at a 3-pointer, but the ball went in and went out, forcing overtime.
Watson had a jumper, two free throws and a 3-pointer as the Bulls rallied from seven down in the fourth to tie it at 86 with just under 3 minutes left.
Watson, who had 13 points in the fourth quarter, hit a 3 from the right side to give Chicago a 93-92 lead with 52.6 seconds to go. But Amir Johnson took a lob pass from Calderon and dunked to give the lead right back to Toronto. Watson then hit 1 of 2 from the line to make it 94-all with 32.2 seconds left.
Notes: DeRozan fell one start short of tying the franchise record. DeRozan, averaging 16.5 points, had started 130 straight games but was injured in the fourth quarter of Friday night's victory over the Knicks when he scored 30 points. The Raptors' record for consecutive starts is 131 set by Alvin Williams. Forbes started for DeRozan ... Richard Hamilton, who has played only 16 games this season, sat out a 10th straight game with a shoulder injury. ... A moment of silence was observed for Lacy J. Banks, the long-time Chicago Sun-Times sports journalist who covered the Bulls during their championship years and also was a minister. Banks died this week.Suggest a correction