Chelsea are joining the battle for Sporting Lisbon midfielder William Carvalho.

Carvalho is a top target for Manchester United and also interesting Real Madrid.

A Bola says Chelsea have joined the scramble for the midfielder's signature and are prepared to make a swap offer.

Chelsea will include Marko Marin, currently on-loan at Sevilla, in part-exchange for the Portugal international.

Sporting so far has referred all interested clubs to Carvalho's €45 million buyout clause.