The Mali international has been a key man for Graham Potter's team for the last two seasons but the 25-year-old is on the cusp of a £25m move to Tottenham.
Bissouma will have a medical at Spurs later this week but the Seagulls have been preparing for his exit for some time.
His departure could allow the likes of Alexis Mac Allister, Jakub Moder, Enock Mwepu, Moises Caicedo and Steven Alzate to nail down that central midfield slot.
Brighton will however be keen to keep their playmaker Leo Trossard. The Belgian was impressive last season and is wanted by new Man United boss Erik ten Hag at Old Trafford.
Trossard is in the final year of his contract and any bid north of £30m could get Albion's serious attention.
Here's how Graham Potter could fill the void next season if his two star players exit.
9. Danny Welbeck - A
Finished last season very well. When he's fit, the former Man U and Arsenal man remains a class act and Brighton's best striker. Yet to announce a new deal but makes sense for all parties if he signs. Photo: Charlie Crowhurst
10. Deniz Undav - A
Prolific for Union SG last season and could be a real star of the Premier League this season. Is he the man to finally apply the finishing touches to Potter-ball? Photo: JOHN THYS
11. Jeremy Sarmiento - A
Highly regarded by Potter and could be the man to fill the void if Trossard departs. The Ecuador international is highly skilful, loves to run at defenders and always looking to make a difference in the final third. Exciting times ahead. Photo: Shaun Botterill