Chelsea midfielder Eden Hazard will be out for a minimum of two weeks, according to Blues boss Jose Mourinho.
The 23-year-old Belgian picked a calf injury in the early stages of the 2-0 win over Paris St-Germain that put Chelsea into the Champions League semi-finals on away goals.
"It is a calf problem, but I have no idea the dimension of his injury," said Mourinho.
"Even when they are not serious, you cannot play for a couple of weeks."
Even if Hazard is only sidelined for a fortnight, it would mean he will miss the Premier League encounters with Swansea and Sunderland.
In addition, it would make him a major doubt for the first leg of the Champions League semi-final.