Giannis Antetokounmpo has been ruled out of Game 6 as the Milwaukee Bucks try to clinch an NBA Finals berth on Saturday against the Atlanta Hawks.

The Bucks moved 3-2 clear in the Eastern Conference Finals after beating the Hawks 123-112 in Game 5 on Thursday, with Antetokounmpo and Atlanta's Trae Young both watching from the sidelines.

Milwaukee confirmed on Saturday several hours ahead of tip-off that the superstar will miss again for Game 6 after he hyperextended his left knee in the Game 4 loss away to the Hawks.

Two-time MVP Antetokounmpo landed awkwardly on his left leg with just over seven minutes remaining in the third quarter in Atlanta, where he jumped up to contest an alley-oop from Lou Williams to Clint Capela, but his knee buckled before he hobbled to the locker room.

The 'Greek Freak' has averaged a career-high 29.2 points in the playoffs, along with 13 rebounds and 5.4 assists.

Antetokounmpo had averaged 28.1 points, 11.0 rebounds and a career best-tying 5.9 assists per game in the regular season.

The Hawks have announced that Young is a game-time decision having missed the past two games with a bone bruise in his right foot.

Young has averaged 29.8 points, 9.5 assists and 2.7 rebounds in his first postseason, having averaged 25.3 points, a career-high 9.4 assists and 3.9 rebounds in the regular season.

Milwaukee are eyeing their first championship since 1971, while they last reached the NBA Finals more than 45 years ago in 1973-74.

The Hawks have not featured in the Finals since their triumphant season 63 years ago when they were still based in St Louis.