Chelsea striker Diego Costa faces a staggering £13m bill for going AWOL this summer.

The Daily Star says Costa is currently in Brazil without his club's permission and was fined two weeks' wages - around £280,000 - on Monday.

If he stays AWOL, he stands to lose around £3m in wages.

And if Costa keeps up his threat to only sign for Atletico Madrid - who are under a transfer embargo until January - Chelsea could take legal action against him.

It is understood they can argue his absence, while he is still under a two-year contract with them, devalues him as an asset.

In the current market, Costa, 28, would be worth at least £50m. That value could drop by around £10m, insiders estimate.

One expert, who asked not be named, said: “I definitely do think they can take him to court.

“I think there are a lot of lawyers out there who are quite keen to take it on."