Liverpool defender Joel Matip appears to be in contention for Tuesday's Champions League scuffle with Atalanta after he returned to training over the weekend.

Naby Keita, who hasn't featured since last month's 7-2 defeat to Aston Villa, could also return after rejoining workouts at the club's Melwood base. However, Thiago Alcantara is a major doubt for the Atalanta match after Jurgen Klopp revealed the midfielder is still sitting out first-team training.

"Naby and Joel trained yesterday fully," Klopp said during Monday's press conference. "I didn't make any decisions yet because we are still only two days after (Saturday's West Ham United) game. We have to wait pretty much until the medical department gives us green or orange or red light, pretty much. So, we wait.

"But we have, in the moment, more center-halves available than we probably will line up together, which is good."

Liverpool have been missing Virgil van Dijk since he suffered a serious knee injury during the Merseyside derby in mid-October. Joe Gomez has been ever-present in the four matches since Van Dijk was sidelined, but his central defensive partner, midfielder Fabinho, was substituted with an injury during last Tuesday's Champions League win over FC Midtjylland.

Nathaniel Phillips, 23, made his Premier League debut alongside Gomez in Saturday's 2-1 win over West Ham while Van Dijk, Fabinho, and Matip were all out of commission.