West Ham United will reportedly only let Dimitri Payet join Manchester United in January if Anthony Martial moves in the opposite direction.
Payet has been heavily linked with a move away from the struggling Hammers during the upcoming transfer window despite being less than a year into a five-and-a-half-year contract.
The France international was one of the standout players of last season but is thought to be dismayed by West Ham's form so far this term, with Slaven Bilic's side sitting just four points clear of the relegation zone approaching the halfway stage of the campaign.
Jose Mourinho has been linked with the playmaker as he looks to invest further in his squad in an attempt to close the gap on the top four, but Le10Sport claims that the Hammers will demand Martial in return.
Martial has struggled to discover his best form so far this season, making just seven Premier League starts and scoring only one goal in the top flight.
However, Mourinho is unlikely to be willing to let the 21-year-old go, with the winger only having moved to Old Trafford in September of last year.
Barney Corkhill
