Former Arsenal midfielder Paul Merson has urged Chelsea to consider signing John Stones from Manchester City this summer.
The Blues have already strengthened their frontline with the arrivals of Hakim Ziyech and Timo Werner, while a new goalkeeper has also been lined up.
However, Merson believes that strengthening in the heart of defence should also be a priority for Chelsea if they are to push on from this term's fourth-placed finish.
Stones has fallen out of favour at City under Pep Guardiola, but Merson feels that the England international could thrive as part of a back three.
"Chelsea don't have a naturally-gifted centre-half who can put his foot on the ball and play," he told Sky Sports News. "I'd go and get John Stones for that, and play him in the middle of the three.
"Then I'd say have Antonio Rudiger and [Andreas] Christensen either side of them. Chelsea love to play out the back, they roll it out every time, so you need someone unbelievably good on the ball.
"If you have pace around them, I think it will help Chelsea; I think Stones would be a great buy, and he has to play in a three.
"Stones has the potential to be great, he really has, but he needs the confidence. At the moment Chelsea have three centre-halves that aren't in the same class as Stones on the ball."
Stones, a £47.5m signing from Everton in August 2016, has made just 15 starts in all competitions this term and is into the final two years of his contract.