Michael Essien suffered a season-wrecking injury yesterday, forcing new Chelsea boss Andre Villas-Boas into raiding his old club for Joao Moutinho.

Blues fear the key midfielder has again damaged knee ¬ligaments and will be out for at least six months and possibly the entire campaign. That would be a huge blow for Villas-Boas just three days into pre-season training. Essien’s likely long-term absence will force him to reassess his transfer plans.

Chelsea will step up attempts to land Luka Modric from Spurs, despite White Hart Lane chief Daniel Levy not wanting to sell at any price.

More pressingly Villas-Boas must recruit a player to fill the void left by Essien, who can play at right-back, as an attacking or holding midfielder and, in ¬emergencies, in central defence.

Moutinho, who plays for Villas-Boas’s former club Porto, is now a serious target despite a £35m buy-out clause.

Essien has been plagued by problems, missing virtually the entire 2008-09 season after anterior cruciate -ligament damage to his right knee. His latest injury came during morning training when he twisted the knee. There will be further tests over the next 48 hours, but it is expected they will show more cruciate trouble.

A third major knee injury in less than three years would raise doubts about Essien’s ability to return at the highest level.

He missed the second half of the 2009-10 season and Ghana’s World Cup campaign, after damaging medial ligaments in his left knee.