The 24-year-old suffered a groin injury while on international duty with Belgium. This ruled the winger out of the Red Devils' UEFA Euro 2020 qualifiers against San Marino and Scotland and denied him his first cap for his country.
Trossard has officially been ruled out of the Seagulls' home game against 12th-placed Burnley on Saturday. And by Potter's estimations the midfielder will not be available until Albion's trip to Aston Villa on Saturday, October 19 at the earliest.
The head coach said: "He just had a feeling in his groin. So we don't think it's as bad as we initially thought.
"But he certainly won't be available at the weekend and we're looking probably at the other side of the next international break.
"That's probably what we're aiming for. But at this early stage it's hard it's hard to put a time scale on it.
"We want to try and avoid injuries when they go away but this happens in football.
Trossard has been a revelation at the Amex since his £15million summer move from Belgian champions Genk. The Belgian livewire struck on his Albion debut, the 1-1 home draw with West Ham United on August 17, and has been a constant threat on the flanks for Potter's side.
While Potter was naturally 'disappointed' in losing Trossard, the Seagulls boss was 'confident' that the 24-year-old could replicate his early season form on his return.
Potter added: "We're all disappointed for him and for us. He's adapted to this level really well and I think there's more to come from him. But you just have to use it for what it is.
"We'll try and get him stronger and, when he comes back, hopefully he'll be able to play at a good level.
"We're really happy with him and how he's contributed to the team. We're confident he can do the same when he comes back."