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.
- Atalanta are set to face their third different English opponent, having previously met Everton in the 2017-18 Europa League (played two, won two) and Manchester City in the Champions League last season (played two, drew one, lost one).
- Since losing their first three group-stage games in the Champions League last season, Atalanta have gone unbeaten in their past five group-stage games in the competition (won three, drew two), including both this season (won one, drew one).
- Excluding qualifiers, Atalanta have only failed to score in one of their past 19 games in major European competition (4-0 v Dinamo Zagreb last season), while they have averaged 2.1 goals per game over the course of this run (40 goals in total).
- Duvan Zapata has been directly involved in six goals in five Champions League starts for Atalanta (four goals and two assists), while he scored twice in their 2-2 draw against Ajax on matchday two.
- Liverpool have lost all three of their away Champions League matches in Italy under manager Jurgen Klopp, losing to Roma in May 2018 and Napoli in October 2018 and September 2019.
- Liverpool have won each of their past three away games in the Champions League group stage, after losing four in a row before this between October 2018 and September 2019 (all under Jurgen Klopp).
- Jurgen Klopp has lost all five of his away Champions League matches in Italy, losing to Napoli (three), Juventus and Roma. Only Sir Alex Ferguson (six) has lost more away Champions League games in Italy than Klopp, while only Luciano Spalletti in England (six out of six) has managed more away games in a country while losing every match.
- Since leaving Basel in January 2014, Mohamed Salah has played more minutes against Atalanta in all competitions without scoring than any other club (263), with his four games against them coming during his spells at Fiorentina and Roma.
- Diogo Jota scored on his first Champions League start for Liverpool in their last game (4-0 v FC Midtjylland), while he could become only the second player to score in his first two starts in the competition for the Reds, following Robbie Keane in 2008.