Chelsea must resolve Diego Costa's future as soon as possible in order to avoid the transfer saga harming Antonio Conte's squad, according to Jimmy Floyd Hasselbaink.
Spain striker Costa, who has been AWOL for over four weeks, has travelled from Brazil to Madrid to put pressure on Chelsea to sell to La Liga club Atletico.
Costa claims that Conte first told him he was not wanted in June via text message, but the Chelsea coach insists that the player was told in January that he would be sold in the summer window.
Atletico are yet to meet Chelsea's £50million valuation of the 28-year-old, but former Stamford Bridge striker Hasselbaink believes that the situation will only end with Costa joining Diego Simeone's side - and the Blues must make it happen soon.
"We know that for the manager, [Costa] can be a difficult character that you have to manage a little bit different," Hasselbaink told Sky Sports' Goals on Sunday show.
"Conte is seeing the future of Chelsea without Costa. That is Conte's prerogative."
Asked how much control Chelsea have over the saga, Hasselbaink said: "There's only one way [to resolve it], I think you have to sell him.
Diego Costa's Chelsea controversies
"If that means you have to sell him to only Ateltico because that's the only place that he wants to go, you have no choice, do you?
"I think Chelsea wants to get rid of the problem - the problem is making a bigger problem by saying where he's going to go and trying to influence the market value, and that will make it even harder.
"That is the individual that is making it very, very difficult to manage - he just doesn't care, he doesn't want to come back.
"But I do believe that Chelsea need to really sort this out ASAP because it doesn't help.
"When a team is successful, it is when things are quiet and calm and they can concentrate on what they have inside."
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Chelsea spent £58million on Alvaro Morata to replace Costa, and though Hasselbaink feels that new signing will make the Blues a better team overall, the Dutch icon still feels Conte needs more attacking options.
"I think you can't replace Costa, because Costa is unique," he added. "They have Morata but I do feel that they need one more. I think Morata is going to a be a brilliant signing.
"What I like about Morata is that he has played for big clubs - Juventus, Real Madrid - so he knows what is expected of him, he knows that there is pressure, and his movement is magnificent.
"He will score goals, he is very good with his back to goal.
"What we forget is how Costa used to play. Costa was really good making trouble with the opposition defence and unsettling them, but his first touch and coming into the midfield was not always the best.
"When he faced the goal and was running at the goal, he was one of the best - so you can now Chelsea a little bit further with a more complete striker in all areas and have a little bit more control in your play."
