Brittney Griner's just days away from returning to the WNBA court -- and anticipation is at an all-time high for Mercury fans -- but the pot is about to get a little sweeter ... 3x Grammy winner Wyclef Jean will be performing a special halftime show in honor of BG's homecoming!

TMZ Sports has learned the Phoenix Mercury have teamed up with The Sum, a new music platform from Anagram Studios, to bring in Jean to perform during their May 21 game against the Chicago Sky at the Footprint Center to celebrate Griner's return on what will be her first home game since the Russia ordeal.

We're told one of the songs Wyclef will sing is Bob Marley’s iconic hit, “One Love” ... where Jean will be joined by 200 fans who will be selected to perform live with the 53-year-old musician.

He will also put on a postgame concert.

Of course, it'll be a party when the star center hits the hardwood in front of hometown Mercury fans this season ... after missing all of last season while she was detained.

The 32-year-old endured nine months in a Russian jail cell/prison camp, before coming home in December thanks to a prisoner swap. There was initially doubt Griner would ever hoop again, but she quickly put that sentiment to bed ... announcing she was coming back.

The WNBA champ ultimately signed a 1-year deal with the Mercury in February ... and said she can't wait to play this upcoming season.

"Look forward to all those moments. Just waking in on the first home game, the grind, the sweat, the blood," Griner said during last month's press conference. "Just taking all that in. I missed it."

And, it's not just BG who's pumped ... Mercury president Vince Kozar can't wait for their home opener!

“May 21 is going to be an unforgettable experience for our fans and we’re thrilled to have the opportunity to have an award-winning artist the caliber of Wyclef Jean join us in celebrating BG’s return and a new Mercury season,” Kozar told us.