The only four signings Chelsea could make to improve this side, including £30m Arsenal target

2) Mats Hummels (Borussia Dortmund)

With John Terry in need of a long-term replacement, Borussia Dortmund centre-back Mats Hummels is another of the world’s top defenders who could make a great addition at Stamford Bridge, though Arsenal and Manchester United also want the £30m man.