Chelsea still have two routes left to qualifiy for next season's Champions League but centre back David Luiz admits that it will be 'tough' to complete the task.

The winners of the Europa League will qualify for Europe's elite competition next term and Chelsea are still alive in that tournament but face a tricky semi-final against German side Eintracht Frankfurt, the first leg of which takes place on Thursday.

If they fail, the second option available to the Blues is through the Premier League top four.

They currently lie in fourth place, two points clear of fifth place Arsenal, three ahead of Manchester United and two behind Tottenham in third.

"Because Tottenham were playing in the Champions League," Luiz told Sky Sports. "It was not easy for them to play game [after] game at the same level.

"They lost some points and gave us the opportunity to come back and now it's four teams for two places, so I think it is tough for everybody."

David Luiz will be without defensive partner Rudiger

Sadly for Antonio Rudiger, a serious knee injury means he will miss the two legs against Eintracht Frankfurt and the rest of the season.

It is a big blow for Chelsea manager Maurizio Sarri as he prepares to face one of European football's deadliest strike forces.

Luka Jovic, Sebastien Haller and Ante Rebic have scored a total of 54 goals between them in all competitions, helping the club to a 100 per cent record in the group stages.

They then went on to beat three Champions League drop-outs in the knockout stages; Shaktar Donetsk, Inter Milan and, in the quarter-finals, a top quality Benfica side.

Sarri also has concerns over experienced Brazilian winger Willian who was carted off following a heavy challenge from Manchester United defender Marcos Rojo last Sunday.

The Italian was optimistic about getting him fit in time for Thursday when he spoke after the Premier League draw at Old Trafford: "Willian is in trouble at the moment but I think it’s only a knock so we can try to recover him."