Former Chelsea fullback Glen Johnson has urged the club to pay what it takes to keep Toni Rudiger and Andreas Christensen.

Both defenders come off contract in June.

"From a business standpoint, it would be a disaster (if both players left)," he told Betting Odds.

"Whether the club wants them both there long term is irrelevant because to replace those two players you're going to have to spend an absolute fortune.

"Even to give them both a year long deal with the intention of selling them after six months would make more sense than letting them walk out on a free.

"It would be terrible business regardless of whether the club fancies them as players or not."