Liverpool winger Luis Diaz has suffered a setback in his comeback from a knee injury.
The 25-year-old Colombian is flying back to the UK from the Reds' training camp in Dubai after complaining of discomfort in the knee he injured in the 3-2 defeat at Arsenal in October.
It had been hoped that former Porto star Diaz could make his return in one of the Reds' upcoming friendlies against Lyon this Sunday or AC Milan next Friday.
However, he is now doubtful for Liverpool's festive programme which begins with their Carabao Cup tie away at Manchester City on December 22 before their return to Premier League action at Aston Villa on Boxing Day.
Diaz is said to have complained of discomfort in the same knee that he injured eight weeks ago after returning to team training on Tuesday, with club medical staff deciding that he should return home for a scan.
Reds boss Jurgen Klopp and his medical staff had hoped that the Dubai trip would be the perfect opportunity to get his squad up to speed ahead of the return from the World Cup break, with the likes of Joel Matip and Naby Keita also building up their fitness.
Diogo Jota is still absent with the calf injury he picked up against Manchester City in October, with the blow also ruling the 25-year-old out of Portugal's World Cup campaign.
Liverpool will hope to have the former Wolves man back in the New Year, but will now be sweating on Diaz's availability.
Speaking before the trip, Klopp said: “I’m happy about the number of players we have for our ‘pre-season’. That’s a good number, the positions are covered.
“We should have two centre-halves, three, four full-backs, enough midfielders, front line pretty much, Lucho (Diaz) is now running outside, looks really good.
“So that’s positive, of course, that’s how we use it.
“But not moaning about the players who are at the World Cup, no. I think it’s enough, to be honest.
“Enough players go and then we need them all back healthy, definitely. Because then it’s a really long season to come, a lot of games and it starts early.
“From that moment on there is no rest again.”
Liverpool chose Dubai as the venue for the training camp due to the close proximity to Qatar, with seven of their players in action at the World Cup this winter.
Of those seven only Uruguay's Darwin Nunez has been knocked out of the tournament, with England pair Jordan Henderson and Trent Alexander-Arnold, Brazil duo Alisson and Fabinho, Netherlands captain Virgil van Dijk and France defender Ibrahima Konate all playing in upcoming quarter-finals.
