West Ham striker Andy Carroll was held at gunpoint after training on Wednesday, Sky sources understand.
A club statement said later on Wednesday night that the police were investigating an incident involving one of their players, believed to be Carroll.
The statement said: "West Ham United can confirm an incident targeting one of our players on Wednesday November 2. The matter is now being handled by the police."
Carroll was driving home from a training session when the suspects demanded that he stop at a junction and gestured they had weapons.
Both men attempted to block his Mercedes G-Wagon when he tried to get away.
They then pursued the 27-year-old as he returned to the team's training ground for help from security staff.
A police statement read: "Police were called at around 12.45pm on Wednesday, November 2, to reports of two males on motorcycles attempting to rob the driver of a car in Romford Road.
"The two men threatened the driver and intimated through gesture that they were in possession of a gun. The motorcyclists attempted to block the car as the driver sought to get away.
"The driver of the car - a man aged in his 20s - was able to manoeuvre away and he called police for assistance. The suspects rode off prior to the arrival of police.
"The driver of the car was spoken to and an allegation of attempted robbery was recorded."
Officers from Redbridge CID are investigating and are yet to make any arrests, the Metropolitan Police said.