Brentford have turned down a £10m bid from West Ham for striker Scott Hogan, according to Sky sources.
Hogan has 18 months left on his current contract at Brentford and is willing to leave in January in order to secure Premier League football.
The 24-year-old is valued at around £15m by the Sky Bet Championship club and Sky sources revealed on Monday that Bundesliga side RB Leipzig were also interested in signing him.
Hogan, who joined Brentford from Rochdale in a £750,000 deal in 2014, has scored 14 goals in 26 appearances this season.
West Ham are also hoping to re-sign Jermain Defoe, despite having their first offer of £6m rejected by Sunderland.
The 34-year-old started his professional career with West Ham and scored 41 goals before leaving for Tottenham in February 2004.
Sky sources understand the Hammers will return with a revised offer as they look to strike a deal to bring Defoe back to east London.