Los Angeles (AFP) - The Atlanta Hawks seized their chance as the Cleveland Cavaliers collapsed late on, erasing a 26-point second-half deficit to stun the National Basketball Association (NBA) champions 126-125 in overtime on Sunday.
The Hawks, who were short-handed when they shocked the Cavs in Cleveland on Friday, never led until overtime.
They took the lead for good on a three-pointer by Mike Muscala with 35 seconds remaining.
Kent Bazemore had a steal and basket with 22 seconds left, and Tim Hardaway Jr made two clinching free throws with 3.6 seconds to play.
Kyrie Irving capped a 45-point game for Cleveland with a basket at the buzzer.
LeBron James had a triple-double of 32 points, 16 rebounds and 10 assists, but fouled out in overtime.
"It wasn't a foul," insisted James, who also voiced his displeasure after the game with a couple of other calls and not getting a time-out granted.
The Cavs led 93-67 after three quarters.
But Atlanta out-scored them 44-18 in the fourth.
Paul Millsap's jump shot at the buzzer to end regulation time knotted the score at 111-111.
The defeat dropped Cleveland, at 51-29, back into a tie with the Boston Celtics for the top seed in the Eastern Conference, although the Cavaliers own the tiebreaker.
Both teams have two regular-season games remaining.
The Hawks were without five key players when they beat the Cavs 114-100 in Cleveland on Friday.
Although they had all but one of those absentees back on Sunday, the Cavaliers appeared to be rolling toward a payback victory until the fourth quarter.
Cleveland hit their first three three-pointers and had seven from beyond the arc as they took a 38-21 lead after one quarter.
Cleveland led 65-46 at half time.
But it unravelled for them in the fourth, as Atlanta scored the first nine points of the quarter to launch their comeback.
"Everything went wrong for us in that fourth quarter, I mean every single thing," said Cavs coach Tyronn Lue.
Even Hawks coach Mike Budenholzer noted: "A fourth quarter like that is hard to explain".
For James, the explanation was simple. "At the start of the fourth, we didn't get stops," he said.
"When you let a team stick around, this is what happens.
"Obviously this has been a very challenging year for us, but we've got two more games and then get ready (for the play-offs). We've had some good moments and some not-so-good moments - like today."
James said he wasn't concerned with the possibility of going into the post-season seeded behind Boston.
"For me, it's never been about trying to get the number one seed," said the four-time NBA Most Valuable Player, who instead wants to see the Cavs playing good basketball heading into the play-offs.
That certainly wasn't the case in the fourth quarter on Sunday.
"That should never happen," Lue said of the collapse. "Especially when we are such a great offensive team, to be out-scored by 26 points in a quarter."
In fact, it was just the third time in NBA history that a team overcame a deficit of 26 or more points in the fourth quarter and won. "
Any time you beat the defending NBA champions, it's huge," Hardaway said, "no matter the circumstances."
The win gives Atlanta a one-game lead over the Milwaukee Bucks for the fifth seed in the Eastern Conference.
DeMar DeRozan scored 35 points as the Toronto Raptors clinched at least the third play-off seed in the NBA's Eastern Conference with a 110-97 victory over the New York Knicks on Sunday.
DeRozan extended his own team record with his 32nd game this season with at least 30 points.
He also joined Vince Carter as the second Raptor to reach 2,000 points in a season.
DeRozan connected on 11 of his 15 shots from the field and also made 13 of 15 free throws in made 11 of 15 shots on his typical combination of mid-range jumpers and drives to the rim.
He also hit 13 of 15 free throws in just under 30 minutes n the floor.
Kyle Lowry added 17 points and 11 assists in his third game back after missing 21 with a right wrist injury.
The Raptors took the lead for good at 76-75 on DeRozan's layup with 25 seconds remaining in the third.
Toronto built their lead early in the fourth, and sealed the game with a 10-0 scoring run that stretched their lead to 98-82 with 5min 36sec to play.
The Raptors could still be seeded as high as second in the East, but only if they beat reigning NBA champions Cleveland Cavaliers in their regular-season finale and the Boston Celtics lose their last two games.