Chelsea legend Gianfranco Zola has claimed that the Blues were right to sell Diego Costa to Atletico Madrid this summer.

The Spain international completed his move to his former club on Tuesday evening despite helping Chelsea to the Premier League title last season.

Costa's replacement, Alvaro Morata, has started his Chelsea career impressively, scoring seven goals in his first eight games following a move from Real Madrid in the summer.

"I have no doubt that it was right for [Costa] to go. He probably has a problem, the team is not made by one player, and I think it's better for him to go," Zola told Sky Sports News.

"On the temporal level Morata is not on the same level as Costa. Technically he is a great player, he obviously has a lot of qualities, good in the air, good feet.

"He has been with Juventus, Real Madrid, big teams, but didn't play regularly, and I want to find out why. And this year I think I'm going to get the answers."

Costa made 120 appearances for Chelsea and scored 59 goals, helping the club to two Premier League titles and an EFL Cup.