Trent Alexander-Arnold could miss his Anfield homecoming after being ruled out for up to six weeks with a hamstring injury.
The Real Madrid star was taken off just three minutes into their 2-1 win over Marseille in the Champions League after pulling up with the blow.
And now he will be sweating over whether he will get to play against Liverpool when his new side visit on November 4.
But more importantly, he could be ruled out of England's next two international breaks in what may be a huge setback to his World Cup hopes.
Thomas Tuchel left the 26-year-old out of his squad for recent qualifiers against Andorra and Serbia, having warned him in May to take defending 'very seriously'.
There is still a chance that he makes the Liverpool game, which directly precedes the second upcoming international break, but he is in a race against time to be ready for it after his left hamstring setback.
Trent Alexander-Arnold could miss his reunion with Liverpool after a hamstring injury
The Real Madrid star will be out for four to six weeks after his hamstring blow against Marseille
Madrid beat Marseille 2-1 thanks to a double from Kylian Mbappe but Xabi Alonso has been left with a headache after his replacement, Dani Carvajal, was given a straight red card following a VAR review for his headbutt on goalkeeper Geronimo Rulli.
Trent has had a tricky start to life in Spain, having been benched for two of the last three LaLiga games following an underwhelming debut.
Unseating captain Carvajal from the right-back role is understandably a challenge given his status in the Spanish capital.
Carvajal, 33, is into his 13th season with the first team and has won 26 trophies in that time, picking up a spate of personal accolades along the way.
Trent was dropped again for Madrid's La Liga fixture with Real Sociedad on the weekend.
Asked about the battle between Alexander-Arnold and Carvajal to become the defacto No 1, Alonso explained that it is far from straightforward for either player to do so.
'Fortunately, we have healthy competition within the team, and they're challenged internally because there are team-mates who are ready,' Alonso said in the past week.
'It also happens in other positions, like centre back or winger. Whoever deserves it will play; it's going to be very repetitive all year.'