"It's too soon right now to decide how he would be because when you get injured, three days is a lot of time, no? We will decide tomorrow or maybe before the game," Pellegrino told a news conference on Friday.
The possible return of Lemina will be a boost for the south coast club as defensive midfielder Oriol Romeu is suspended for the clash after picking up his fifth yellow card of the season in the 3-0 defeat at Liverpool last weekend.
"Oriol is an important player for us. But I think we've got enough in our squad to try and replace him. Also it is an opportunity for other players," the manager said.
Southampton, who are 14th in the table after 12 games, with three wins, four draws and five defeats, have struggled up front this season scoring nine goals and Pellegrino said he could sign a new striker when the January transfer window opens.
"Always we are looking for a player that can improve our squad. It's not easy because every team has got power. Two or three clubs are fighting for the same player but we are open to see the market and to check in which situation we can improve."
Everton, who were beaten 5-1 at Atalanta in the Europa League on Thursday, are 16th in the league with 12 points after three wins, three draws and six defeats.
(Reporting by Shrivathsa Sridhar in Bengaluru Editing by Jeremy Gaunt)
