A crestfallen Giannis Antetokounmpo declared "there's no failure in sports" after the Milwaukee Bucks were consigned to a stunning first-round playoff exit by the Miami Heat.

The Heat won Game 5 128-126 in overtime at Fiserv Forum on Wednesday to take the series 4-1. 

Inspired by Jimmy Butler, who scored 42 points, Miami became the sixth number eight seed to beat a top seed and the first since the Philadelphia 76ers in 2012.

The Heat were two points down with 2.1 seconds to go, prompting Erik Spoelstra to call a timeout and draw up a play that Butler did not feel was the right approach, so his coach changed his mind.

That paid off when Gabe Vincent threw a pass to Butler, who tied up the game to force overtime and the Heat went on to eliminate the Bucks.

Bucks superstar Antetokounmpo, who scored 38 points and took 20 rebounds, dismissed talk of the team being a failure this season.

"There's no failure in sports," he said. "There's good days, bad days. Some days you're able to be successful. Some days you're not. Some days it's your turn.

"Some days it's not your turn. That's what sports is about. You don't always win.

"It’s not a failure, it's steps to success. There's always steps to it. You work towards a goal. Michael Jordan played 15 years, won six championships. The other nine years was a failure? No."

Spoelstra lavished praise on Butler after he stepped up once again to make a huge impact.

"He’s desperate and urgent and maniacal and sometimes psychotic about the will to try to win," Spoelstra said of Butler.

"He'll make everybody in the building feel it. That's why he is us and we are him. That's the way we operate as well."