Mwepu has missed Albion’s last two games due to a groin issue and is likely to be on the bench.
Jeremy Sarmiento (hamstring) and long-term absentee Jakub Moder (knee) remain unavailable.
West Ham expect to have winger Said Benrahma available again for the trip to the Amex Stadium.
Benrahma missed last weekend’s 2-2 draw against Manchester City with an ankle problem, but should be in contention to return to the squad.
Defender Issa Diop (ankle) remains a doubt, while long-serving midfielder Mark Noble could make his final appearance for the club before he retires.
Meanwhile, Potter says Pascal Gross and Danny Welbeck are close to agreeing new deals at the Amex Stadium.
The future of the key Seagulls pair had been uncertain, with their current contracts set to expire in the summer.
“Pascal and Danny are really close, I think, to agreeing everything for next year,” he said.
“I think it’s just a matter of time, a bit of formality, so that’s great.
“They’re two guys that have played massive roles for us,” continued Potter.
Here’s how Albion could line-up for this one….