Everton midfielder Mikel Arteta has suffered a minor set-back in his recovery from injury.
The Spanish star, who suffered a cruciate knee ligament injury in February, has had minor surgery to remove an infection from the same knee and is now recovering.
Manager David Moyes said: "Mikel has needed to have a 'wash out' on his knee after doctors found an infection.
"It is a set-back for him. However we can't say how long it has put him back."
hugely influential
Arteta has been a hugely influential player for the Merseysiders since joining on loan from Real Sociedad in January 2005.
He impressed during 10 Premier League appearances, scoring once and earning a £2m permanent switch.
He has since netted 17 goals in 115 Barclays Premier League starts but has not played since the 0-0 draw at Newcatle United in February 2009.
