Chelsea are being kept updated on Douglas Costa's fitness ahead of a £20million summer swoop. The Brazil international is a long-term target of Jose Mourinho, who is keen to bring the Shakhtar Donestsk midfielder to Stamford Bridge. And the Blues will revive their interest in the 24-year-old ahead of next season provided they receive assurances over a long-standing knee concern. Brazil international midfielder Douglas Costa is a long-term target of Chelsea and Jose Mourinho . Mourinho and Chelsea are receiving fitness updates about Costa as they want assurances about a knee injury . Costa (left) has also reportedly caught the attention of Real Madrid, Barcelona, Arsenal and Liverpool . Chelsea are being regularly updated on Costa's fitness and will press ahead with a move if they are satisfied with the joint in question. Costa will spark a transfer scramble this summer with Shakhtar Donetsk ready to sell their prized-asset. Shakhtar chiefs are now open to selling Costa and talks with third parties over his departure are underway. The Ukrainian side hope to spark a bidding war for the midfielder in attempt to maximise his transfer fee, with a starting price of £25million. Costa is open to joining a Barclays Premier League club, but wants to be playing Champions League football. However, a host of Europe's top sides will also be in the running to land Costa this summer, Real Madrid and Barcelona among them. Costa (left) plays for Brazil but has dual Portuguese nationality, lowering fears of work permit issues . Costa is said to be open to moving to the Premier League but wants to join a club in the Champions League . Costa could make the switch from Shakhtar Donetsk to Stamford Bridge for £20million . Arsenal have had Costa watched extensively, while Manchester United and Liverpool have both been linked with a move. But Chelsea are set to lead the charge having tracked the Brazil international for two years. Despite playing for Brazil, Costa has dual Portuguese nationality so should not face work permit issues.
Shakhtar Donetsk midfielder Douglas Costa is a long-term Chelsea target . Chelsea want assurances about a long-standing knee concern . Costa is also a target for Real Madrid, Barcelona and Manchester United . READ: Douglas Costa dreaming of summer move to Chelsea . CLICK HERE for all the latest Chelsea news .