Chelsea must cough up big to land Barcelona midfielder Sergi Roberto.

Sport says the London club could bid up to £6.5million, but all approaches have so far been knocked back.

Although Roberto has barely featured in the first team so far, new coach Tito Vilanova has plans to incorporate him next season, especially if Seydou Keita departs this summer.

However, if the Mali international stays, Barca may be tempted to let him go on a deal that would include a buy-back clause - much like Romeu's £4.3m deal last summer.