Hull FC centre Kirk Yeaman has undergone surgery on his injured foot.
The 28-year-old England international was already facing a fortnight out after injuring his wrist in last Friday night's 22-10 win at St Helens.
Meanwhile, Black and Whites prop Mark O'Meley has been handed a one-game ban by the RFL for the Grade B offence of making dangerous contact with Saints forward Tony Puletua.
Hull coach Peter Gentle must now make changes for Sunday's visit of Widnes.
"We felt it was an opportune time to get Kirk in for his operation as he's been struggling with a minor problem," he said.
"He had surgery on Saturday and we'll know more shortly about how long his rehabilitation period is likely to be."
Yeaman enjoyed his best-ever season in 2011, running in 24 tries to end up the third highest scorer in Super League.