Former Chelsea fullback Glen Johnson is baffled by the sale of Mateo Kovacic to Manchester City.

The Croatia international left Chelsea last week for the Treble winners.

"I think he's going to be one of the biggest losses for Chelsea this summer," Johnson told BetFred. "They've got decent money for him, but they've sold him to a better side that he's going to improve.

"It was obviously a tough decision for Chelsea to sell him to City, but he's going to thrive at Manchester City as he's going to be surrounded by world-class players and he himself is a world-class player.

"It's very good business from Manchester City's side. They have top quality players in all positions, so Kovacic doesn't even need to be an all-round midfielder, he just needs to be a rock for them in midfield and then play it to the fellow world-class player that's next to him."

He added: "It will be embarrassing for Chelsea if the players they've sold improve at their Premier League rivals and it would be even more embarrassing if the players they've signed for big money fail to work out,' he said.

"They're certainly allowing some of their big names to go to their rivals.

"Let's face it, Chelsea are behind the top four at the moment and they're selling some of their best players to those teams above them, but they do have to recoup a lot of the money they've spent and time will tell if they're doing the right thing."