Chelsea defenders John Terry and Robert Huth will undergo scans on injuries sustained during the club's training camp in Spain.
Terry and Huth were both taking part in a practice match at the La Manga complex when they mistimed a tackle.
They flew back from Spain and the seriousness of their injuries was being assessed in London.
The club's official website revealed: "A collision between the two in training led to the decision to return them to London, where their leg injuries can be properly assessed.
"This is a precautionary measure and it is hoped that neither will miss any competitive action."
The England international said before his departure from Spain: "Robert and me mistimed a tackle and kicked each other.
"We've both got the same problem on the ankles. We stayed down for about five minutes and, for Robert, that's unusual.
"We got up and carried on training but four or five hours later, we were on the physio's bench. I've got to go back for x-rays and scans, and we'll know a bit more after that.
"It may be the ligaments but obviously I hope it's not too serious. We will have to wait and see."