The on-loan Chelsea forward suffered an ankle injury when Gareth Barry collided with him during the 4-0 defeat to Liverpool at Anfield, and early indications pointed to possible ligament damage.
"He has his ankle in a cast. We will assess it but it doesn't look too good at the moment," boss Roberto Martinez said of the injury.
However, tests have confirmed that the Belgian's injury is not as serious as first feared and he should make a recovery in the upcoming weeks.
"There is no ligament damage and the injury is not as bad as we first thought. It will be a case of weeks rather than months," Martinez added.