Chelsea & Man Utd stars among 12 players clubs MUST keep hold of this summer, plus Raheem Sterling

3) Diego Costa (Chelsea)

One of the best strikers in the world, Chelsea must do all they can not to lose Diego Costa to Real Madrid after just one season.

4) Sergio Aguero (Manchester City)

Another top target for Madrid, Sergio Aguero is Manchester City’s best hope of glory next season after he outshone his team-mates in 2014/15.