Captain Lewis Dunk is closing in on a return from a knee problem but will not be involved, while midfielders Enock Mwepu (hamstring) and Yves Bissouma (Africa Cup of Nations) also remain unavailable.
The injury to Lallana is particular cause for concern as it leaves Potter short in the vital central midfield area as Mwepu and Bissouma are also missing. It could mean a different role for Alexis Mac Allister or a chance for Steven Alzate.
"It is always disappointing when we lose a player," said Potter of Lallana's injury. "I don't think it will be serious to be honest. It will keep him out of this one and maybe for the weekend (Leicester), we will see.
"When you play Chelsea, in that area of the pitch, it is so hard to control and do that. He will be a miss for that but it will be a chance for others to come in and take that chance.
"All year we have had players missing, key players - Danny [Welbeck] Lewis [Dunk] Adam Webster, Yves Bissouma and we have managed to find ways and that is credit to the guys.
"You cannot be successful with XI you have to have a group that is ready to fight. Whichever XI plays, we will have that on Tuesday night."
Full-back Tariq Lamptey is fit to take on his former club after a slight groin issue restricted him to a second-half cameo during Friday’s 1-1 draw with Crystal Palace.
"He is [fit], confirmed Potter. "He had a problem last week, it was more precautionary which is why he didn’t start against Crystal Palace, he’s available for selection."
Asked if he thought Chelsea regret letting him go, Potter added: "I wouldn’t say that, I would say that Tariq has got huge respect for Chelsea as a club, he’s very appreciate of what they helped him with, it’s his first club.
"Sometimes these things happen. Chelsea are a very successful club, they’ve won the Champions League, so I am not sure they are regretful. It’s a part of football and life. I am sure there’s a lot of respect on both sides.
"Tariq did a brave thing in leaving somewhere that was safe for him, to come and play football, but credit to Chelsea, they’ve got a fantastic model."
Andreas Christensen will miss out again for Chelsea due to coronavirus isolation.
Trevoh Chalobah remains sidelined with a thigh problem, with Reece James a longer-term absentee due to a hamstring injury.
Ben Chilwell is out for the season after knee surgery, with Edouard Mendy at the Africa Cup of Nations with Senegal.
Brighton provisional squad: Sanchez, Scherpen, Lamptey, Burn, Veltman, Webster, Cucurella, Roberts, Turns, Offiah, Gross, Alzate, March, Caicedo, Mac Allister, Moder, Leonard, Trossard, Maupay, Welbeck, Ferguson.
Chelsea provisional squad: Arrizabalaga, Bettinelli, Rudiger, Sarr, Silva, Azpilicueta, Alonso, Kovacic, Jorginho, Kante, Loftus-Cheek, Niguez, Barkley, Hudson-Odoi, Pulisic, Ziyech, Mount, Werner, Havertz, Lukaku.