Chelsea midfielder Oriol Romeu has been ruled out for the rest of the season after undergoing surgery on a knee injury suffered during the weekend's Premier League win over Sunderland.

The Spanish midfielder has withdrawn from The Blues squad for the upcoming World Club Cup and is expected to be absent for the next six months having had anterior cruciate reconstruction surgery and medial meniscus repair on Monday.

Under-19 midfielder George Saville, who was an unused substitute in the League Cup win over Manchester United, will replace Romeu in the squad in Japan, despite having never made a first-team appearance for Chelsea.

Oriol Romeu
Romeu will miss at least six months of the season.

Romeu was replaced by Oscar after 20 minutes at the Stadium of Light on Saturday and the injury comes as a significant blow in his hopes to stamping his mark on a Chelsea side under the stewardship of interim boss Rafa Benitez.

After making just five appearances during Roberto di Matteo's eight-month reign in charge, Romeu has featured in all but one of Benitez's five matches at the helm, in the absence of Frank Lampard.

Having made 33 appearances since his switch from Barca in the summer of 2011, Romeu's appearances have been sporadic at Stamford Bridge.

While his own first-team aspirations have taken a dent with this latest injury blow, his lengthy absent throws into doubt his particpation in the June's Under-21 European Championship, while it may warn off interest from Barcelona in resigning the 21 year old this summer.

The Catalan giants can activate a clause in Romeu's contract to resign him this coming summer, having turned down the opportunity in the previous transfer window, but fears over his long-term fitness are likely to deter the club from making such a move.

Romeu joins John Terry on the sidelines for the Club World Cup with the Chelsea skipper ruled out with a knee injury picked up in last month's draw with Manchester City.

But Lampard, who played 11 minutes against Sunderland at the weekend, does return to the squad and is in contention to start the semi-final against Mexican champions Monterrey on Thursday.

Despite just one win in their last eight league games, Chelsea go into the competition as big favourites, with Copa Libertadores winners Corinthians likely to be their main threat as Benitez seeks to win his second World Club Cup crown.

The Brazilian side face Al-Ahly in the other semi-final, with the respective winners facing off in Sunday's final.

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