Footage has emerged of Christian Pulisic getting injured as he ran out for half-time with Thomas Tuchel looking on confused at Stamford Bridge.
It came during Chelsea’s shock 5-2 loss to West Brom which saw Callum Robinson and Matheus Pereira each score twice.
That has seen Tuchel’s unbeaten streak as Blues boss come to an end in spectacular fashion.
Thiago Silva was also sent off after two yellow cards in the second-half and Chelsea capitulated.
After two quickfire goals at the end of the half from the Baggies, there was no surprise to see a change made at the break by Tuchel.
However, it came as a bit of a shock to see Pulisic come off – who had scored earlier for the home side.
Mason Mount came on for the 22-year-old, who went on to net a consolation goal.
But it has since emerged that the former Borussia Dortmund star was injured, tweaking his hamstring as he ran out with the sides getting ready to restart the match at half-time.
Footage has emerged of Pulisic jogging out of the tunnel at Stamford Bridge, running 10 yards to a cone before turning back.
The cameras turned to Tuchel, who looked dumbfounded by what had just happened in front of him.
It is the ninth injury the American has suffered since his move from the Bundesliga to Chelsea, though the extent of this problem is yet to come to light.
And with a crucial clash against Porto coming next in the Champions League, Tuchel knows his side must improve quickly.
“After the red card we could not adapt to the situation,” he said.
“Even in the second half what could go wrong went wrong after the red card.
“Hopefully it is a big wake up call for all of us, myself included. We did big mistakes after the two yellow cards. Today was impossible for us to adapt to the situation.
“It is not typical for us. Today we conceded two of them and changed completely the momentum.
“At half time we tried to calm them down and give them confidence, but every shot was a goal from them. We had big chances and hit the post. It clearly wasn’t our day today.”