The England full-back limped off at Stamford Bridge after a tangle with Jarrod Bowen
Ben Chilwell was forced out of Chelsea’s home game with West Ham within 10 minutes with an apparent ankle injury.
The full-back had a coming together with Hammers midfielder Jarrod Bowen and turned his ankle.
Chilwell was treated on the pitch and after a lengthy discussion with the medical staff, he attempted to play on.
However, it did not last long as he went down again clutching his right ankle and was immediately replaced by Emerson.
It will be a blow to Blues manager Frank Lampard to lose the left-back ahead of the busy festive period.
The whole season has been busy so far due to the late start on account of the coronavirus pandemic, but games come fast in England over Christmas and New Year.
Following the Premier League game with West Ham, Chelsea face Arsenal on Boxing Day and Aston Villa on December 28.
They then welcome in 2021 with a home game against Pep Guardiola’s Manchester City.
The full-back positions are an area of concern for Chelsea, as right-back Reece James was ruled out of the game with West Ham on account of a knee injury.
Cesar Azpilicueta was drafted in as replacement for James, while Emerson is an experienced figure on the other side of the back line.
But with games coming quick, Lampard will hope the injury to Chilwell is a minor one.
While Lampard is still restricted to three substitutions, he has more players to choose from on the bench as that number has been lifted to nine.
Lampard feels it would be better for player welfare to have more substitutions.
“When we spoke about it as managers, the overriding factor from managers, whether they were maybe for or against, was that this is a case of player welfare, making sure we are looking after players and giving them the best opportunity to play at optimum level and not putting them at risk and such, because of the uncertain times and the schedule,” Lampard said.
“And that schedule gets tougher, for instance we play two games in three days over Christmas. So I think it would have been really beneficial for player welfare. Normally the modern-day player welfare comes out on top, I don’t think it quite has this time.
“But the decision’s been made, and we carry on.”