Doc Rivers was frustrated by the Philadelphia 76ers' second unit after his side gave up a big lead against the New York Knicks.

The Sixers went down 108-97 in New York on Sunday, despite taking a 21-point lead in the first quarter.

Philadelphia's advantage was cut to just two by halftime, and although they restored a three-point cushion heading into the final quarter, they could not hold out.

Having seen his team surrender a 21-point lead for the second game in a week, coach Rivers bemoaned the play of those he had to call on from the bench.

"I thought our second unit came in and struggled," Rivers told reporters.

"This is the second time that has happened. The same thing happened in Orlando.

"Both times, we were scoring too easy. The second group comes in and thinks this is an offensive game and they didn't see the reason the first group got the lead was because of defense."

Joel Embiid, Tobias Harris and James Harden started and each posted double-doubles for the 76ers, yet Tyrese Maxey was the only substitute to get into double figures for points (12).

In contrast, the Knicks bench accounted for 37 points, with Evan Fournier putting up 17 of them.

Rivers did, however, insist it was "not just a bench loss".

"We've been good at that. Just because one half doesn't work, you don't vacate the unit," he said.

"That's what guys do who lose a lot. So they didn't play well, though honestly, I didn't think that's why we lost the game.

"I hate that the numbers look like it was the bench: it was everybody. This was a team loss and I made that clear.

"We'll sit and look and we'll see minus-24 and plus-34s, our stars were in some of that too when Fournier was making those shots, and so I just thought it was a team loss. I thought it was more mental and emotional than just playing basketball.

"I thought we were just not strong. Mentally, I thought they were the mentally tougher team and they deserve to win."

Embiid, who led the game with 31 points, 14 rebounds and three assists, added: "It's never easy.

"A 20-point lead in the NBA, that's nothing. Any team can come back and that's what they did tonight."