According to court docs, obtained by TMZ Sports, the New Orleans Saints wide receiver says he agreed to rent a mansion in the Bel-Air area from Feb. 4 to April 5.

The place was awesome -- it had six bedrooms, eight bathrooms and an incredible gym, media room and pool.

Thomas claims the deal with the owner was simple ... he says he agreed to pay $60,000 a month in rent, as well as a $60,000 deposit.

Thomas says the owner promised to leave the NFL player alone too ... allowing him to train for the 2021 season without any interruptions.

Thomas claims he paid $120k for the two-month rental term, and also paid the $60k security deposit in full just before moving in.

But, Thomas says after he moved in, there was nothing but drama with the place.

The 28-year-old says there were issues with the pad's pool, garage doors and kitchen appliances. Thomas also says reps from the place "repeatedly" showed up to the home unannounced, interrupting Thomas' workouts.

To make matters worse, Thomas says the mansion's owner refused to give back any portion of his $60k security deposit after he moved out in April.

Thomas is now suing for breach of lease and more, and is asking for more than $1,000,000 in damages.

It's all VERY interesting ... considering the drama currently going down with Thomas and his Saints team.

Reportedly, New Orleans wanted Thomas to have surgery on his injured ankle following the 2020 season ... right around the time the receiver began renting the Bel-Air mansion.

But, Michael opted to try to heal the injury on his own ... and allegedly didn't communicate much -- if at all -- with the Saints during that process.