Diddy‘s spending his first Memorial Day behind bars … ringing in the long weekend with basketball and BBQ chicken instead of Ciroc and yacht parties this year.

TMZ has the scoop on what the rap mogul will be doing in MDC Brooklyn for the holiday on Monday — and, it looks like there are plenty of options if he feels like engaging in some friendly competition with his fellow inmates.

Diddy and the MDC crew can play dominoes, spades and board games to determine the champion of 4 North — the dormitory-style wing of the prison away from general population, reserved for high-profile inmates.

And, to finish off the day, chicken and rice — or tofu for the vegetarians or vegans behind bars — pinto beans, canned corn and whole wheat bread.

All in all, it sounds like a fine weekend for someone in the midst of the biggest legal battle of his life … with the third week of testimony in Diddy’s federal sex trafficking and racketeering case set to begin Tuesday.

The trial’s already featured a series of bombshell moments … from Cassie claiming Diddy had an escort urinate in her mouth to Kid Cudi telling the jury about Diddy allegedly blowing up his car.

Diddy’s longtime assistant, Capricorn Clark, is expected to testify next week.