Chelsea hit by Essien blow on first day back

Chelsea midfielder Michael Essien has suffered a serious injury to his right knee during pre-season training.

The 28-year-old was last night undergoing a series of tests to the injury, which occurred on Thursday during the first full day of Chelsea's training programme under new manager Andre Villas-Boas, but club insiders fear the worst.

Unconfirmed reports yesterday claimed he had suffered a torn cruciate ligament, which, if confirmed, would be the third knee ligament injury suffered by Essien in three years and would raise concerns that he might never regain full fitness again. The usual recovery period for such an injury is six months.

Essien tore his anterior cruciate ligament in his right knee in September 2008 and missed six months, returning in March the following year.

Then he tore the medial ligament in his left knee while training with Ghana before the African Cup of Nations in January 2010 and suffered complications following surgery. The knee continued to swell up and the player underwent four operations in a fortnight before he was eventually ruled out for the remainder of the season, including the World Cup finals in South Africa.

He recovered last season and played 43 games in Chelsea's disappointing campaign, but he never seemed to play at full power.

Last night Chelsea issued a statement which said: "Michael Essien suffered an injury to his right knee during training this week. He will undergo tests over the next few days to determine the extent of that injury. Until we have the full results of those tests we will not be commenting further."

If the injury is as serious as suspected, it would be a major blow for Chelsea and would provide the first test for Villas-Boas – as he takes over from Carlo Ancelotti, who was sacked on the final day of the season – knowing only winning a major trophy will save him from a similar fate. It would also make it far more likely that Villas-Boas would be in the market for a similar player to bolster his squad, with a move for Porto's 24-year-old central midfielder Joao Moutinho a possibility.

At his peak, Essien is very much the complete midfielder: physically intimidating, relentlessly energetic, but also possessing a deft touch and a powerful shot from distance.

Essien has played 224 games for Chelsea since joining from Lyons for £24.4m in August 2005, and he was voted the club's player of the season in 2006-07.

Last summer he signed a two-year contract extension, worth £80,000 a week, that keeps him at Stamford Bridge until 2015.

Chelsea are hopeful they can replace English with Lille's medical chief Franck Le Gall, who also worked with French internationals at the national football centre at Clairefontaine.

Chelsea last night confirmed the appointment of Michael Emenalo as the club's technical director, overseeing the scouting operation, to replace Frank Arnesen. Emenalo, 46, was controversially promoted to assistant first-team coach to Ancelotti last November, following the dismissal of Ray Wilkins, against the wishes of the manager. Villas-Boas has successfully managed to manoeuvre the Nigerian, who sat on the bench alongside Ancelotti for much of last season, away from the first team. Villas-Boas will also have a greater say in the buying of players than his predecessors, and has brought in his own opposition scout in Daniel Sousa, greatly reducing the importance of Emenalo's role.