Jimmy Butler conjured a dazzling 56-point performance as the Miami Heat came from behind to shove the top-seeded Milwaukee Bucks to the brink of elimination from the NBA playoffs Monday, while LeBron James led an overtime rally to give the Los Angeles Lakers a commanding series lead over the Memphis Grizzlies.

In an electrifying battle at Miami's Kaseya Center, Butler all but single-handedly led Miami to a 119-114 win that leaves the Bucks 3-1 down in the best-of-seven Eastern Conference first-round series.

In the Western Conference, the second-seeded Grizzlies are also staring down the barrel of an early playoff exit after the Lakers claimed a 117-111 victory to take a 3-1 series lead.

James finished with 22 points, 20 rebounds and seven assists and grabbed a game-tying driving layup with 0.8 seconds remaining in the fourth quarter to force overtime.

James then marshalled the Lakers superbly in overtime, scoring four points to put the Lakers in sight of the conference semi-finals.

But the performance of the day came in Miami, where Butler's 56-point haul was the joint fourth-highest individual scoring total in an NBA playoff game ever.

Only Michael Jordan (63 points), Elgin Baylor (61) and Donovan Mitchell (57) have scored more in a postseason game.

Milwaukee, who welcomed Giannis Antetokounmpo back into their lineup after a two-game injury absence, had looked to be cruising towards victory after leading from the opening seconds and keeping Miami at arm's length throughout.

- 'Complete team effort' -

Milwaukee led by 14 points early in the fourth quarter and seemed to be poised to square the series at two games apiece after a ruthless shooting performance from Brook Lopez, with Antetokounmpo providing scoring support.

But Butler led an astonishing late 13-0 run to transform the contest and with the crowd roaring him on, scored 21 points in the fourth quarter to leave the Bucks shellshocked in defeat.

Miami coach Erik Spoelstra saluted Butler's basketball intelligence.

"He's one of the most intelligent basketball players in this association," said Spoelstra.

"He understands what we're trying to do and he understands what they're trying to do -- and they're a very good team."

Butler said his solo masterpiece was the result of a "complete team effort."

"I know everybody sees the 56 points, but if my team-mates aren't looking to get me the ball, or setting great screens, where I can get to my right or my left or the free throw line, this game's a lot different," Butler said.

"A lot of shots went in tonight. But my team-mates kept feeding me the ball and telling me to attack. When you've got team-mates like that, good things happen."

Crucially, Butler's haul included 22 points in the first quarter, a burst of scoring that helped Miami stay just in touch.

- Lakers leave it late -

No other Miami player broke 20 points, with Bam Adebayo the next highest Miami scorer with 15 points. Only two other Miami players cracked double figures.

Lopez finished with 36 points and 11 rebounds while Antetokounmpo made a triple double on his return with 26 points, 10 rebounds and 13 assists.

"We had our opportunities in the fourth quarter but we didn't make enough plays at either end, and they did," said Bucks coach Mike Budenholzer, whose team must now win game five in Milwaukee on Wednesday to stay alive.

In Los Angeles, the Lakers also left it late before subduing a resurgent Grizzlies in overtime.

Memphis looked well-placed to level the series after opening up a seven-point lead with just over five minutes remaining in the fourth quarter.

But the Lakers' D'Angelo Russell reeled off three straight three-pointers to turn the game around and give the hosts a 99-97 lead.

A frantic final few minutes saw Memphis take a 104-102 lead with just seconds left on the clock after a sensational behind-the-back pass from Ja Morant set up Desmond Bane for a running layup.

But James conjured his game-tying drive to force overtime and the Lakers tightened up defensively to close out the win.

"We had a next-play, refuse-to-quit mentality," Lakers coach Darvin Ham said. "I'm so proud of the way we fought.

"We had moments in the game that weren't too pretty. But we just kept chipping away, didn't get discouraged and didn't fall apart."

Ham reserved special praise for the leadership of the 38-year-old James down the stretch.

"All of his travels, all of the phenomenal things he's accomplished, he still has that passion, that grit to be on top," Ham said. "And that's what you saw... that's who he's been his entire career."

Bane led the Memphis scoring with 36 points while Morant finished with 22.