By Deputy Editor Harvey Byrne

West Ham sent scouts to watch midfielder Gelson Martins play for Sporting Lisbon against Rio Ave on Sunday night, according to a report.

Portuguese news outlet A Bola has claimed that representatives from the Hammers alongside Manchester City, Manchester United and Chelsea were in attendance with the 21-year-old being watched closely.

However, the midfielder does have a buyout clause in his contract, which stands at a mega £51.4million.

The clause is more than double the Hammers current transfer record after the signing of Andre Ayew for £20.5million from Swansea in the summer.

It is also stated that Lisbon are intending to review the contract of Martins, who still has five years left on his current deal due to the youngster being the lowest paid player in the squad.

The right winger joined Lisbon’s youth system in 2010 after starting off at Benfica.

He made his debut in 2014 at the age of 19 and has gone on to play in 41 encounters for his current club scoring seven goals.

The youngster has made six appearances for Lisbon this season, scoring two goals and providing four assists and he was also handed a start against Real Madrid last week.

In other West Ham transfer news, the Hammers are keeping tabs on Galatasary midfielder Bruma.