According to The Sun, West Ham are appealing Raul Jimenez's work permit ruling, with the Atletico Madrid striker's move to Upton Park in doubt.
The Hammers have been busy in the transfer market this summer, but they are yet to add a new striker to their ranks - and with Andy Carroll and Enner Valencia both ruled out with injuries, new manager Slaven Bilic is in desperate need of a new striker ahead of the Premier League season.
The opening game of the season against Arsenal is just days away, and the Hammers are now in a race against time to land their top target.
The Sun report that West Ham have agreed a season-long loan deal for Atletico Madrid hitman Jimenez, with a £1.4m fee involved in the deal taking him to Upton Park.
However, the report also states that, despite Jimenez now being a regular for the Mexican national team, new guidelines implemented by The FA mean that the 24-year-old will not qualify for a work permit - and West Ham are challenging that decision.
It's unclear how long it will take to reach a new outcome, but West Ham's move for Jimenez is now in jeopardy, which could force Bilic to look elsewhere.
Jimenez may have only scored one goal in 27 games for Atletico, but his record of 39 goals in 102 games for Club America and eight in 36 caps for Mexico suggest that he is better than his Atletico record states.
With height, power and aerial ability, Jimenez could be the ideal centre forward for West Ham whilst Carroll is sidelined, whilst his above-average speed would also offer something that Carroll doesn't.
A deal may now be difficult, but West Ham are keen to push the move through, suggesting that they have every confidence that Jimenez can be a success in the Premier League; all they need now is clearance from The FA to complete the deal.