The 37-year-old former basketball player – who was previously married to reality TV star Khloe Kardashian – was spotted slumped on a chair at 2am in his VIP booth at Bootsy Bellows nightspot on the Sunset Strip.
In a clip of the aftermath, obtained by TMZ Sports, Lamar can be seen slumped on a chair before being helped up.
His rep told the publication he had collapsed due to dehydration after an intense workout earlier that day, and added that it was very hot in the club.
Lamar is “doing great” following the incident.
The person who shot the video clip alleged to the gossip website that he saw the former Los Angeles Lakers star drinking for several hours beforehand.
It’s not the first time Lamar has collapsed. He nearly died following an overdose at the Love Ranch brothel in Las Vegas, Nevada in 2015.
He has since admitted he was in a “dark place” at the time.
Lamar previously said: “Being in that damn brothel and thinking I was going to just rest a little bit. I wasn’t in a good place mentally before that incident happened. Me and my wife at the time were going through some things. I was in a dark place.
“I guess they say everything happens for a reason. I guess the reason is I’m here. I can tell the story.”
Lamar – who was married to Khloe from 2009 to 2016 – has since entered rehab and vowed to turn his life around. He recently confirmed plans to release a tell-all book.
He said: “I have a book coming out, an autobiography about my life. [The book will cover] everything. Everything. It’s a free-for-all. [It’ll be] open about everything that’s been going on in my life, about the past.”