Michail Antonio has established himself as a key player for West Ham. Arfa Griffiths/West Ham United via Getty Images

Chelsea are monitoring West Ham United's Michail Antonio, sources close to the player have told ESPN FC.

Antonio has been West Ham's star performer this season, with the 26-year-old having excelled in a number of different roles.

He has played at right-back, left wing, right wing and up front and he is the club's top scorer with eight goals.

Chelsea are in the market for attacking reinforcements after selling Oscar, and Antonio's versatility has brought him to the attention of Blues boss Antonio Conte.

He impressed Conte in West Ham's EFL Cup win over Chelsea earlier this season and could play in a variety of positions in the manager's 3-5-2 formation -- a system also used by West Ham boss Slaven Bilic.

Antonio's homegrown status also makes him an attractive proposition to Chelsea as they look to boost their quota.

The former Nottingham Forest and Sheffield Wednesday player had a significant role as West Ham finished seventh last season and his form this term saw him called up to the England squad.