Chelsea have been dealt a major blow on the eve of the new season with summer arrival Christopher Nkunku requiring surgery on the knee injury suffered against Borussia Dortmund last week.
Nkunku damaged the meniscus in his knee and it is feared he could be sidelined for around two months.
Nkunku, who joined this window from RB Leipzig in a deal that was agreed last year, was one of Chelsea’s standout performers during their tour of America, scoring three times.
But he was hurt early on in their final game against Borussia Dortmund in the early hours of Thursday morning, eventually being forced off midway through the first half.
Nkunku was seen with an ice pack on his left knee and there were initial hopes the damage was not too serious though it has proved to be more serious than first anticipated.
The pitch at Soldier Field was in bad condition following an Ed Sheeran concert the Saturday which had a standing area for a section of the audience on the pitch.
Chelsea players appeared visibly concerned as they walked out onto it though head coach Mauricio Pochettino refused to blame the surface and insisted the setback was suffered in an early challenge on Nkunku.
Pochettino said: ‘The doctors are checking him hopefully it is not a big issue but when he fell in the action maybe it was a penalty. Had the chance to score.
‘He feels something in his knee but hopefully it is not a big issue and that he can be [back] quickly with the team. Now we need a few days to assess him and until we get back to London it is difficult to know.
‘I didn’t see the action but it not about to complaining. Always we take some risks because the pitch is not perfect because they are using it for different sports and that is sometimes the risk of the tour, yes.
‘But I think it was a bit unlucky in the situation but we cannot complain about the pitch and to blame the pitch for why he suffered the injury. For me it was bad luck.’