The Spaniard, substituted while on international duty in midweek, is claimed to have missed training on Thursday and will be monitored ahead of the trip to the Britannia Stadium
The Daily Mirror reports that the striker had a CAT scan after being taken off during Spain’s 2-1 friendly defeat to Italy in Bari on Wednesday, and claims that Torres was unable to train on Thursday as a result.
The concussion is believed to be mild, but manager Andre Villas-Boas is reportedly unlikely to risk playing Torres on Sunday, with Didier Drogba ready to play in his absence.
Torres will be monitored by Chelsea over the next 24 hours before a final decision is made.
Defender David Luiz is also rumoured to be out of the game, having also reportedly not trained on Thursday as he continues to recover from his Copa America exertions this summer, due to which the Brazilian missed much of the Blues’ pre-season games.
Young forward Daniel Sturridge will definitely be unavailable as he serves the first of a three-game suspension incurred by a red card in the final game of last season when playing for Bolton.
Serbian defender Branislav Ivanovic may yet be fit, though, after reportedly returning to training from an ankle injury.