Speaking to Casino Site, Gus Poyet said: "If I were Chelsea, I would sign a defender. They can play the ones that are currently there, but when you lose a player like Wesley Fofana for the whole season, you need to react.
"I'm sure that he was one of the four main central defenders. Which kind of player you get, whether it's a young one or an experienced player, is up to Mauricio Pochettino. But they definitely need a defender.
"Out of the defenders out there, the one I like is Manchester City's target, Josko Gvardiol, so it's going to be difficult to get him. But it's about the characteristics, and that's a question for Pochettino."
Gvardiol appeared to be all set to sign for Man City but it has gone surprisingly quiet in the last few weeks as RB Leipzig refuse to lower their asking price.
The Bundesliga side are demanding £87 million for the 21-year-old centre-back, a figure that the Premier League champions are unwilling to entertain.
