Defender Joel Matip and midfielder Naby Keita face late fitness tests before Liverpool’s Champions League game at Atalanta on Tuesday (20:00 GMT).
The pair trained on Sunday, but midfielder Thiago Alcantara was absent as he recovers from a knee injury.
“We have to wait until the medical department gives us a green, orange or red light,” said manager Jurgen Klopp.
Liverpool have won both of their Champions League games this season and are top of Group D.
Meanwhile, Atalanta, who reached the quarter-finals of the 2019-20 competition, have picked up four points from their opening two matches and are second.
This will be Liverpool’s first European match against the Italian side and Klopp is expecting a tough game.
“They obviously have a really good atmosphere, a good mood and are a proper fighting unit,” said the German.
“They are very well organised; play their system with 100% conviction, they know exactly what everybody has to do.
“I know how good they are. I actually enjoyed the analysis, I enjoyed watching them because it’s really interesting.”
Premier League leaders Liverpool will be playing their sixth game in 18 days.
Matip has only featured twice this season and missed the past four matches, while Keita has been absent for five games because of a muscle injury.
Centre-half Virgil van Dijk is expected to miss most of the season with a cruciate knee ligament injury, while stand-in defender Fabinho sustained a hamstring problem in the 2-0 home win against Danish side FC Midtjylland last week.
“We have, in the moment, more centre-halves available than we probably will line up together, which is good,” added Klopp.