Trae Young has scored 48 points while Clint Capela converted a go-ahead put-back with 29.8 seconds left to guide the Atlanta Hawks to an upset 116-113 win over the Milwaukee Bucks to open the NBA's Eastern Conference finals.

The Hawks improved to 6-2 in road play-off games this year and handed the Bucks their first home loss of the post-season.

"I felt we've built ourselves to be able to play on the road," Hawks coach Nate McMillan said.

"I've told them that. They're built for this."

Game 2 of the best-of-seven series is Friday night in Milwaukee.

Giannis Antetokounmpo had 34 points, 12 rebounds and nine assists for the heavily-favoured Bucks while Jrue Holiday added 33 points and 10 assists.

Young was two points off his career high.

"It's been fun playing with this group. We just keep fighting to the end, no matter what the score is.," Young said.

"That's what we're going to do. We're going to keep fighting."

John Collins added 23 points and 15 rebounds for the Hawks while Capela finished the game with 12 points and 19 rebounds.

Khris Middleton missed a potential tying 3-pointer in the closing seconds.

"Offensively, it didn't seem like we moved very well," Bucks coach Mike Budenholzer said.

Antetokounmpo scored the first six points in a 9-0 run that turned a 98-96 deficit into a 105-98 advantage with 4 minutes 18 second left.

Holiday capped that spurt by sinking a 3-pointer after Antetokounmpo got the rebound on his own missed free throw.

But the Hawks scored the next five points, and the game went back and forth from there.

Middleton missed a pull-up jumper with about 43 seconds left with Milwaukee up 111-110.

Young missed a driving lay-up attempt, but Capela grabbed the rebound and scored to put the Hawks ahead for good.

After Milwaukee's Pat Connaughton shot an air-ball on a 3-pointer, Young made two free throws with 17.3 seconds remaining.

Antetokounmpo made a pair of free throws with 5.3 seconds left, but Young brought the lead back to three and closed the scoring by sinking two free throws of his own with 4.6 seconds remaining.