Chelsea will be without goalkeeper Petr Cech for up to a month after he suffering a knee injury in training.
Cech fell awkwardly at the end of Chelsea's training session on Wednesday and was taken for scans, which subsequently revealed he had sustained a medial ligament injury.
Chelsea boss Andre Villas-Boas has confirmed the 29-year-old will be out of action for three to four weeks and as a result will miss this weekend's clash with West Brom and next week's clash with Norwich.
"Petr Cech yesterday suffered a medial ligament injury and will be out for three to four weeks," Villas-Boas confirmed.
"It was the end of training, a normal training incident. He fell awkwardly with his weight on top of him.
"We expected much worse when we saw the incident."
With new signing Thibaud Courtois having joined Atletico Madrid on a season-long loan, Villas-Boas is likely to call on Hilario for the Baggies tie on Saturday.