The Miami Heat sealed top seeding in the Eastern Conference playoffs on Thursday as the Boston Celtics and Philadelphia 76ers suffered defeats on the road against the Milwaukee Bucks and Toronto Raptors.

The Celtics were outgunned 127-121 by the Bucks in Milwaukee while the Raptors edged out Philadelphia 119-114 in Toronto.

The combined results left Miami with an unassailable lead at the top of the Eastern Conference at 52-28 with two regular season games remaining.

Milwaukee's victory over Boston leaves the Bucks in pole position to claim the second seed in the East.

Milwaukee are 50-30 with games against the lowly Detroit Pistons on Friday before a road game in Cleveland on Sunday.

Boston meanwhile are 50-31 with just a final regular season road game on Sunday against the Memphis Grizzlies remaining.

The Celtics looked to have clawed their way back into a winning position at the Bucks' Fiserv Forum after trailing by 13 points near the end of the first half, taking a five-point lead at 114-109 midway through the fourth quarter.

But after Marcus Smart's driving layup put Boston ahead at 121-118 with just over two minutes remaining, momentum swung back to Milwaukee.

Bobby Portis's three-pointer from 27 feet leveled the scores, and then Giannis Antetokounmpo's free throw put the Bucks ahead at 122-121.

A Jrue Holiday layup made it 124-121 Milwaukee and then a wide-open missed layup by Boston's Daniel Theis allowed Antetokounmpo to add another free throw for a 125-121 lead.

A George Hill steal and layup sealed the Celtics' fate at 127-121.

Antetokounmpo and Holiday led the Bucks scorers with 29 point each while Khris Middleton added 22 points.

Smart led the Boston scorers with 29 points.

"It was a tight game, but the guys found a way to win another close game, so some positives from that," Milwaukee coach Mike Budenholzer said.

In Toronto, Pascal Siakam’s 37-point triple-double sparked the Raptors to victory over the Sixers.

Siakam finished with 37 points, 11 rebounds and 12 assists in the Raptors win, while Gary Trent Jr added 30.

Joel Embiid led the Sixers' scoring with 30 points and 10 rebounds while Tyrese Maxey chipped in with 22 points.

"Offensively we lost our rhythm, we lost our pace," Philadelphia coach Doc Rivers said. "That's happened about three times now. We've got to keep our pace going. A frustrating loss."

In the Western Conference, meanwhile, the Denver Nuggets wrapped up the last automatic playoff place with a 122-109 win over Memphis.

Reigning MVP Nikola Jokic led the Nuggets with 35 points, 16 rebounds and six assists.

The victory ended the Minnesota Timberwolves' faint hopes of sneaking into the automatic playoff spots.

The Timberwolves had kept their hopes alive briefly with a 127-121 victory over the Antonio Spurs, led by a career-high 49 points from Anthony Edwards.