West Ham are trying to conclude a £20m-plus deal to sign forward Jarrod Bowen from Championship club Hull City.
Crystal Palace had appeared favourites to sign Bowen, one of the most highly-rated players outside the top-flight.
But West Ham, desperate to reinforce David Moyes’ squad for a battle to avoid the drop, have edged in front.
It has been suggested West Ham have arranged a medical for Friday lunchtime but club sources have said the deal is still not done.
Bowen, 23, has scored 16 goals this season for Hull City, who are 13th in the Championship.