Chelsea are sweating on the fitness of Romelu Lukaku ahead of this weekend's game with Aston Villa.
The Belgian continued his impressive form on international duty, scoring three times in games against Estonia and the Czech Republic.
He is suspended for Belgium’s World Cup qualifier against Belarus on Wednesday which was set to hand him a few extra days rest.
But Lukaku will now have to undergo surgery having struggled "with a minor thigh issue"
"I’ll have a scan of my thigh first," he told HLN after Belgium’s win against Czech Republic.
"I have been struggling with a minor issue for a while. And then I will return to Chelsea."
It means the Blues could be without their £97.5m signing for the trip to Villa Park on Saturday ahead of what is a hectic week.
Chelsea begin their Champions League campaign on Tuesday with a game against Zenit St Petersburg before they host title rivals Manchester City a week on Saturday.
If Lukaku is absent Thomas Tuchel will have to bring Timo Werner back into the fold or play without a recognised striker, which he has done previously.
The German is also waiting to see whether N'Golo Kante will be available.
He has an ankle problem and was forced off at half time in the 1-1 draw with Liverpool on August 28.
Kante reported for international duty with France last Monday but subsequently pulled out of the squad for their three World Cup qualifiers.
Lukaku has recently opened up about the manner in which he returned to Chelsea, having left the club in 2014.
He confessed to being in a "deep hole" at Manchester United and didn't want to down tools to force through his Inter Milan exit.
"I was only going to leave Inter Milan for Chelsea," Lukaku told HLN. "Kids love Real Madrid, Barcelona, Manchester United. And Chelsea for me, everyone knows what Chelsea means to me.
"If they ask me, why would I say no? I only realised that Chelsea was serious at the third offer. So it was €100m (£85m), then it was €105m (£90m), and then it went to €110m (£94m). Then I knew, this is truly serious.
"I was in a deep hole at Man United. I didn't want to go behind Inter's back.
"So after training I went to [Inter boss Simone] Inzaghi's office. I didn't want to ruin the atmosphere because I was no longer with my head in Milan. So I asked him: please find an agreement."
