Lucas Leiva
Lucas has played an integral role for Liverpool this season.

Liverpool's preparations for the Merseyside derby against Everton have been further disrupted by the news that Lucas Leiva faces a scan to learn the extent of a knee injury which could force him out for the foreseeable future.

The Brazilian replaced Philippe Coutinho at half time in the 2-2 draw with Aston Villa but was replaced after 66 minutes with a knee complaint which threatens to disrupt his season.

Lucas' injury comes days before the FA Cup fourth round visit to AFC Bournemouth and a week prior to the visit of an Everton side to Anfield who trail their Merseyside rivals by just a single point in the race for the fourth Champions League spot.

Manager Brendan Rodgers said: "He clashed knees with an opponent, so we'll just see how he is.

"He just felt a little click in his knee. Hopefully it's not too serious. We'll not know for the next 24 to 48 hours."

Lucas has been a crucial facet of Liverpool's impressive campaign and was much missed during the draw with Paul Lambert's Villa.

If ruled out, Lucas would become the sixth injury absentee for the trip across Stanley Park, and his loss would be a crucial blow to Liverpool's hopes of flirting with a late tilt for the Premier League title.

The remainder of the Reds' injury problems lie in defence – the source of their recent problems in the league - with Daniel Agger, Mamadou Sakho, John Flanagan, Jose Enrique and Sebastian Coates all out.

Kolo Toure and Martin Skrtel have been entrusted with organising the Liverpool back-four but the ease with which Villa scored two first half goals shows Rodgers has plenty of work to do to keep the club's European ambitions on track.

Tottenham Hotspur's win over Swansea City saw Tim Sherwood's side draw level on points with Liverpool who were boosted by Everton's failure to beat West Bromwich Albion on Monday.