LeBron James Hit Diddy's Bday Party After Lakers Loss

The Lakers got smoked by the Toronto Raptors on Sunday night -- and LeBron James didn't exactly play great -- but he was still in the mood to party afterward.

TMZ Sports spotted James on the way into Diddy's 49th birthday party at Ysabel in West Hollywood ... where he celebrated with the likes of LLCOOLJ, Kourtney Kardashian, Usher, Mary J Blige and Kid Capri.

James pulled up with his wife, Savannah, in his $340k Rolls Royce but made it clear he didn't wanna talk basketball.

Here's why ... Bron and the Lakers lost to the Raptors 121 to 107 ... and LeBron only put up 18 points (he didn't even play the 4th quarter).

In the locker room, Bron told reporters it felt like the team got "hit in the mouth" and they didn't have a response.

Too bad, because there were a TON of big stars who came out to see the Lakers at Staples Center including Denzel Washington, Odell Beckham, Brian Ortega, Canelo Alvarez, Chris Bosh and more.

Lakers don't play again until Wednesday ... so, why not go out and party?