Antonio Conte today admitted he couldn't guarantee that Diego Costa will stay at Chelsea this season.

Costa missed his second game in a row on the club's pre-season tour of the USA with a minor back injury as Chelsea lost 3-2 to Real Madrid.

His former club Atletico Madrid, who sold him to Chelsea for £32m in 2014, have spent all summer trying to lure back to Vicente Calderon.

Chelsea have insisted throughout that the 27-year-old is not for sale and have written two warning letters to the La Liga club to tell them to stop pursuing him.

But on the same day that Chelsea closed in on a £60m switch for Romelu Lukaku, Conte wasn't able to confirm that Costa still has a long-term future at the club.

He said: “I speak for today and today Costa is Chelsea’s player. Tomorrow if you ask me if Costa will remain with us, I don’t know.

“I can say that today Costa is a Chelsea player. He didn’t play in these games because of injury and if he solves the injury and I see in training he’s in good shape it can be possible to see him in the next game against AC Milan [on Wednesday]. But I can tell you only this."

Costa has been Chelsea's top scorer the past two seasons, but has been the subject of a lot of controversy during his stay in west London.

It is understood he has asked the club to grant him a move back to Atletico on more than one occasion, only for him to be denied.

Chelsea won't sell him unless they have at least one replacement lined up because they already feel they are one striker short in the squad.

Blues' fans had been given hope earlier on Saturday that Atletico had finally given up their pursuit of Costa when they signed Kevin Gameiro from Sevilla for £28m.

Funds are fairly limited at Diego Simeone's side and Gameiro was seen as the back-up choice in case a move for Costa failed.

Real Madrid vs Chelsea: In Pictures 7 show all Real Madrid vs Chelsea: In Pictures 1/7 Eden Hazard dinks the ball home to try and mount a late fightback. AFP/Getty Images 2/7 Mateo Kovacic and Oscar in a tangle. Getty Images 3/7 Marcelo scored two and set up another in a first-half blitz. Duane Burleson/Getty Images 4/7 Eden Hazard rounds Ruben Yanez to score. AFP/Getty Images 5/7 Arsenal and Chelsea target Alvaro Morata was in action for Real Madrid. AFP/Getty Images 6/7 Mariano Diaz celebrates his goal against Chelsea. JAY LAPRETE/AFP/Getty Images 7/7 Michigan Stadium saw great support for both teams. Getty Images 1/7 Eden Hazard dinks the ball home to try and mount a late fightback. AFP/Getty Images 2/7 Mateo Kovacic and Oscar in a tangle. Getty Images 3/7 Marcelo scored two and set up another in a first-half blitz. Duane Burleson/Getty Images 4/7 Eden Hazard rounds Ruben Yanez to score. AFP/Getty Images 5/7 Arsenal and Chelsea target Alvaro Morata was in action for Real Madrid. AFP/Getty Images 6/7 Mariano Diaz celebrates his goal against Chelsea. JAY LAPRETE/AFP/Getty Images 7/7 Michigan Stadium saw great support for both teams. Getty Images

Lukaku, who left Chelsea for Everton in a £28m deal two years ago, looks certain to be one addition.

But Conte refused to comment on Lukaku's potential arrival, saying: "I don’t want to speak about players of other teams. This is not respectful for the club or for my players. I prefer not to speak."

Chelsea faced another of their main forward targets in Real Madrid forward Alvaro Morata this afternoon in Michigan Stadium.

Real have put a £67m asking price on his head and that looked to have scared Chelsea off.

But if Costa is on the verge of a return to the Spanish capital, then they are bound to renew their interest.

He failed to impress in front of a crowd of 105,826, the biggest attendance Chelsea have played in front of in their history, in the absence of Real Madrid stars like Cristiano Ronaldo and Gareth Bale.

But when asked about Morata's future at the club, Real Madrid coach Zinedine Zidane insisted he was going nowhere.

He said: “Morata is a Real Madrid player. We are delighted to have him back to his original home and he will remain a Real Madrid player.

“He’s just starting and he needs more time to get his rhythm. I saw him play well, he held it up and returned to help defend."