West Ham are looking at Southampton's Shane Long and in-form Brentford striker Scott Hogan as alternative January targets should Sunderland remain unwilling to sell Jermain Defoe.
Hammers boss Slaven Bilic is keen to strengthen up front in the new window given Andre Ayew's depature to the African Cup of Nations, a long-term injury to Diafra Sakho and the disappointing form of loanees Simone Zaza and Jonathan Calleri.
Defoe, 34, is believed to favour a return to his former club with West Ham also confident he can operate at the top level for another 18 months.
But the final decision rests with Black Cats boss David Moyes who needs all the firepower at his disposal in the club's relegation battle and Defoe would be taking a major risk by handing in a transfer request in case it's not accepted.