Goal understands the Spain international will depart Stamford Bridge on an initial six-month loan deal, with the Liga outfit having the option to buy Morata for £43.7m ($57m) at the end of the season. There is understood to be a further £4.4m ($5.7m) in loan fees.
His departure from west London has been signed off following the confirmation of Gonzalo Higuain's arrival on a loan deal from Juventus, with the Argentina international reuniting with his former boss at Napoli, Maurizio Sarri.
And Sarri confirmed his happiness at having finally landed Higuain's signature after Morata made it clear that he wanted to leave the club during the January transfer window
“I think that Morata is a very good player," he told reporters ahead of Thursday's Carabao Cup semi-final second leg against Tottenham. "I think that Morata has the characteristics for playing in my team
"But Morata, one month ago, said he wanted to play in another team.
"So it was really very difficult for him to give us the 100 per cent for his mental situation. But I think that Morata is potentially a very important player. From the physical and technical point of view, he is a very good player and suitable for my football.
"The situation changed in the last month. So we needed to change. I don't know [about the transfer market]. As you know very well, I don't want to follow the market day by day. I don't know the actual situation.
"Morata told me 10 days ago that there was an opportunity in Spain, but I don't know where.
"We have some problems in scoring. Higuain usually is able to score 25 or 30 goals every season. But, as I told you before, in the market in January it's very difficult to secure a very important striker.
"Gonzalo was in a situation that we could try to buy him, and so we decided to try for Higuain."
Higuain was not registered in time to be eligible for the meeting with Mauricio Pochettino's side as the Blues look to overturn a 1-0 deficit following the first leg at Wembley.
Chelsea do have the option to make the deal permanent either this summer or at the end of the 2019-20 campaign should they extend the current loan move - a signal that the club's normal policy of not offering long-term contracts to players over the age of 30 might be changing.
And Sarri believes that 31-year-old Higuain is not too old to have a long term future in the English capital
“Thirty-one and 32 is not really very old. I think that, for a striker, it's very difficult to score with continuity when they are 22 or 23. So the best is from 27 to 32 or 33.
"I don't know exactly the details of the contract, though, so it's very difficult for me to answer."
"It's up to him. He has to score, first of all. I think that, for a long-term contract, he has to do very well. He has to play. He has to score. He has to be useful for the team.”
Away from the transfer market, Chelsea have been in declining form over the winter period, leading to increased focus on their new manager and his players.
Chelsea's most recent match saw them well beaten at the Emirates Stadium in a 2-0 Premier League defeat to Arsenal. and Sarri caused a stir post-match by claiming that his players were "extremely difficult to motivate".
The Italian, though, does not believe that his words should be construed as a warning to his players.
“I didn't attack my players," he continued. "I told only my opinion about our problems. But I wanted them to realise the problem - I think it's my job.
"Of course, I have the responsibility also of the mental point of view, so the performance was my fault, of course.
"But I said I am in trouble because it's very difficult to motivate them, but I didn't want to attack them. I didn't attack my players. I only texplained to the journalists my problem.
"They are very good boys. With this little problem that I think I can help them (with).
"But I didn't want to attack them. If we have a problem, I think we have to discuss the problem. We have to try and find the reason for the problem. We have to try and do something to improve. I cannot see a big problem with this. Why? Why would I keep it a secret?
“I don't know why, otherwise it would have been easy for me. I don't know exactly the reason, or maybe there are 100 reasons. It's difficult, but we have to try something to improve in this. We are changing something in training, something in pre-match.
"We are trying to do our best, of course. But, for us, it's a problem – not always, but even in some very important matches. So it's really very strange.
"When you play against Arsenal or Tottenham, you usually arrive at the match with a very high level of motivation and determination, but we made mistakes in this kind of match.
"So it's very strange and we need to improve. But they agree with me. I discussed it with the players after the match, and I said to them the same things as in the press conference. It's not a big problem. I want to be direct with them in private and in public.
"I said that, for me, it was very difficult to motivate them. Not impossible, but it's very difficult.”