Chelsea manager Jose Mourinho has warned Juan Mata that he must prove his worth in a wide role to become a regular starter under his management.

Mata has made three appearances in Chelsea's six games so far this season, with one of those coming from the bench in Wednesday's 2-1 home defeat against Basel.

Mourinho has declared that he wants to use Oscar in an advanced central area, a position in which Mata has enjoyed great success during two seasons at Stamford Bridge.

The Portuguese coach has challenged Mata to nail down a starting spot on the right flank, but with the responsibility of tracking back when the Blues lose possession.

He told Sky Sports News: "I want to build with Oscar as my number 10. I want the other two players, from the side (wings), to adapt to that reality and to learn how to do things that they were not ready to do before.

"But [Mata] played against Everton from the beginning and you can analyse his performance. And he played against Basel, not like Demba Ba or Jon Obi Mikel, coming in to rescue the game, but he came on when the team was winning 1-0 and when he had specific tasks to do.

"It's part of a process with him. It's a problem I enjoy. I've never worked so hard as I'm doing now."

The Blues are without a win in any of their last four games in all competitions ahead of Fulham's visit to Stamford Bridge later today.