Chelsea would be above Man Utd and Liverpool if they had this player - Danny Mills

Costa infamously fell out with Chelsea boss Antonio Conte last summer.

Conte text the Spain striker, telling him he was no longer wanted at the club.

Costa went on to rejoin Atletico Madrid and was replaced at Stamford Bridge by Alvaro Morata.

Chelsea have struggled and sit fifth in the table, with their hopes of finishing in the top four all but over.

Mills believes Costa would have made a massive difference and lifted the Blues over the likes of Manchester United, Liverpool and Tottenham.

“I know they’ve brought in Morata, who’s a good player,” Mills said on Sky Sports.

“But when you lose a player like Diego Costa, his goals, the way that he plays, the way he leads the line.

“Willian and Hazard were brilliant yesterday (against West Ham). If you would have put Costa in that, if you put Costa in that Chelsea team, they’re probably second in the league at the moment.

“Obviously (Manchester) City have been excellent but they would be a lot, lot better.

“Conte has had an issue with recruitment ever since and at the start of the season he changed the formation, because he was playing three in midfield instead of the normal two because (Tiemoue) Bakayoko was in there a lot.

“That then detracted, Willian didn’t play the first half of the season hardly at all.

“So he’s had this issue with recruitment, he had the same issue in the January transfer window. He’s not been happy since last summer.”