Valencia doubtful for Arsenal clash
The Ecuador international required stitches after cutting his big toe on a broken cup.
West Ham manager Sam Allardyce is now sweating on the forward's fitness ahead of the short trip to the Emirates Stadium.
"Enner has had an accident at home and has cut his big toe quite severely on a broken cup. It has been stitched," Allardyce said.
"We're not sure if he will be considered for this game. It was a freak accident."
A fine first half of the 2014-15 campaign left West Ham fans dreaming of European football at Upton Park next season.
However, a run of one win in their past 11 Premier League matches has seen West Ham slip to 10th and the pressure grow on Allardyce.
There were signs of improvement in West Ham's last outing that ended in a 1-0 defeat to Chelsea.
And having not played last weekend as they were already eliminated from the FA Cup, Allardyce is hopeful the break can do his team good ahead of another London derby.
"Hopefully the little bit of rest physically and mentally will help us win more games in the last 10," he added.
"I've been doing it for 10 years and the stats say we should have a break as it reduces the risk of injuries in the new year.
"We've gone to Arsenal a couple of times and got in front, but unfortunately the leads haven't lasted very long.
"All we can hope is that we produce the level of performance we did against Chelsea and hope that is good enough."