NBA MVP Joel Embiid has scored 33 points as his Philadelphia 76ers easily claimed a 3-2 lead in the Eastern Conference semi-finals, beating the Boston Celtics 115-103 on the road.

And in Denver, Nikola Jokic had a record-breaking 10th career playoffs triple-double as he led the Nuggets to a 118-102 win over Phoenix and a 3-2 lead in the Western Conference semis in Tuesday night's other game.

The 76ers led by as many as 21 points in the fourth quarter as home fans booed the Celtics in Boston.

Philadelphia can close out the series and advance to the conference finals when they host Game 6 on Thursday night - they haven't reached that stage of the playoffs since 2001.

It was the third straight 30-point game in the series for Embiid, who also had seven rebounds, four blocks and three 3-pointers.

Tyrese Maxey added 30 points and six 3-pointers. James Harden finished with 17 points, 10 assists and eight rebounds.

Jayson Tatum led Boston with 36 points but was just 11 of 27 from the field. Jaylen Brown finished with 24 points. The Celtics went 12 of 38 from the 3-point line.

The previous two occasions the 76ers were in a second-round series that was tied 2-2, they were blown out in Game 5 - a 36-point loss to Toronto in 2019 and 35-point loss to Miami last season.

Not this time.

"It's not over. We have to get one more," Embiid said. "All of us. We have to show up."

If there's any solace for Boston, it's that the Celtics survived this exact scenario last year in this round, overcoming a 3-2 deficit to defeat the Milwaukee Bucks.

"If you're not willing to get dirty, if you're not willing to pretty much bleed, if you're not willing to break something...then you shouldn't be on that court," Celtics guard Marcus Smart said. "Because that's what it is. That's what the playoffs are about."

In Denver, Jokic had 29 points, 13 rebounds and 12 assists as the Nuggets regained the series lead against the Suns, breaking a tie with Wilt Chamberlain for most career triple-doubles in the playoffs by a centre in NBA history.

Game 6 is Thursday night in Phoenix. The home team has won every game in the series. If that holds true again, the decisive winner-take-all clash will come Sunday back in Denver, where the top-seeded Nuggets own the NBA's best home record at 39-7, including 5-0 in the playoffs.

For the Nuggets, Michael Porter bounced back from a bad night in Game 4 with 19 points on 5-of-8 shooting from long range.

Devin Booker has been outstanding for the Suns in the playoffs and he scored 28 points but missed 11 of 19 shots while Kevin Durant chipped in 26 points for Phoenix.

Before the game, Jokic shared a warm pregame embrace -- and the basketball -- with Ishbia 48 hours after their kerfuffle over a loose ball in Phoenix in Game 4 resulted in a technical foul and a $US25,000 fine for the Nuggets big man.

"I was hoping he was going to pay my fine," Jokic cracked after the game.