Lamar Odom -- The NBA Drug Trail

Lamar Odom was deep into drugs while he was playing for the Dallas Mavericks and there is evidence he was doing the exact same thing while playing for the Lakers ... TMZ has learned.

Sources connected to a Westin hotel in Memphis tell TMZ ... in March of 2012, shortly before Lamar was cut from the Mavs, he stayed in one of the guest rooms while his team was in town playing the Grizzlies.

Our sources say when Lamar left, hotel employees found major carpet damage ... including quarter-sized burn marks. The damage was so bad, the hotel had to replace the carpeting in the room.

Our sources say hotel employees also found white powder on the desk blotter and the room reeked of noxious smoke. Our sources say it was obvious there was serious drug use going on in the hotel room.

The Westin is one of numerous hotels where NBA players stay when they're on the road. TMZ has contacted a number of these hotels in various cities. We've learned from several hotel employees ... they had complained about the state of the rooms when Lamar left -- similar to what happened in Memphis -- and this was while he was playing for the Lakers.

Our sources say no one on the Mavs knew Lamar was a substance abuser while he was on the team, but everyone knew something was seriously wrong with him.

We're told that during at least part of the time he was playing for the Mavs, Lamar was smoking Oxycontin and cocaine.

Odom's problems were so severe, he was cut from the Mavs mid-season and paid in full just so he would go away.

TMZ broke the story ... the drug use escalated to crack -- and we're told Lamar's level of crack use is now alarming and life-threatening.