Liverpool manager Jurgen Klopp missed training on Wednesday after being admitted to hospital having felt unwell.
Klopp has undergone checks by medical staff and will be released this evening so will not require an overnight stay.
The full squad returned to Melwood from international duty to train late on Wednesday afternoon but it was without Klopp, who by then was already at hospital having decided to admit himself.
"He is being assessed by doctors and will be absent from training on Wednesday as a result," said a statement from Liverpool.
"There are currently no plans for Jurgen to remain in hospital beyond his appointment and he will therefore return home this evening; however, he may require further check-ups in the coming days.
"The club urges that the privacy of Jurgen, his family and other patients is respected while attending hospital visits."
Liverpool face Southampton on Saturday but there is no indication yet when Klopp, who is scheduled to face the media on Friday for his pre-match press conference, will return to training or whether he will be in charge at the weekend.
The 50-year-old German, who last week made a trip to South Africa for a charity event, has missed a game before back in February 2016 at home to Sunderland, when he was hospitalised after suffering appendicitis.
On that occasion assistants Peter Krawietz and Zeljko Buvac oversaw the team's 2-2 draw and they, plus coach Pepijn Lijnders, took training in the manager's absence.
Eight more players returned to Melwood on Wednesday after international duty.
Philippe Coutinho and Roberto Firmino, who both played for Brazil against England at Wembley, Simon Mignolet (Belgium) and Joe Gomez, Dominic Solanke and Trent Alexander-Arnold - who represented England at senior and under-21 level - and Wales duo Ben Woodburn and Danny Ward were all present.
Scotland's Andrew Robertson returned on Monday with Croatia's Dejan Lovren and Senegal's Sadio Mane coming back on Tuesday.
Mane returned early from international duty after complaining of another problem with his hamstring but Liverpool remain optimistic about the extent of the issue and he has not yet been ruled out for the weekend.
Captain Jordan Henderson also returned to full training after recovering from a thigh injury which forced him to miss the 4-1 win over West Ham before the international break and pull out of England's friendlies against Germany and Brazil.
Midfielder Adam Lallana's long-awaited return has edged closer after he joined full training for the first time since August.
The England international has not played a competitive match after sustaining a thigh injury in a pre-season friendly.
Lallana spent the last fortnight completing a bespoke fitness plan and has now finally joined the rest of his team-mates ahead of the visit of his former club Southampton.