#4 Gelson Martins (Sporting Lisbon)
The Portuguese is a product of Sporting Lisbon's youth academy and he is also a part of the Portugal squad participating in the World Cup in Russia. Some have even called him the future 'Cristiano Ronaldo' as well.
His breakthrough season came in 2015/16 campaign and since then he hasn't looked back and has developed with those performances.
Chelsea have been scouting the winger but are likely to face competition from Spurs, Manchester City , Liverpool and Arsenal. He has recently also requested Sporting Lisbon to terminate the contract, so that he can move for free.
His main strengths are his pace, trickery, dribbling skills and passing. If Willian leaves Stamford Bridge he should be a like to like replacement for him, because his style of play is similar to Chelsea's Brazilian star.
If Martins wants to take his career and game to next level he should leave Sporting and Chelsea would be a good destination for him and he just 22 years old as well.