Chelsea have had an ambitious £46m bid rejected for Atletico Madrid midfielder Koke according to Metro.
The Blues have struggled for form recently and desperately need to add new players to improve their squad.
Koke is also a target for Bayern Munich but the Colchoneros are determined to keep all their key players this summer.
At the start of the month, the 23-year-old told i3 Sports that Atletico Madrid are ready to compete for the La Liga title this season.
"The team are training well and working really, really hard, and I believe that this season we can compete with Real Madrid and Barcelona," he said.
"Last year we finished as champions, but in the past season it was Barcelona and Real Madrid all over again.
"We've had a lot of good changes recently, so I think that this season we can do something important.
I really think the new players can bring some positive changes to the team."