With Wayne Rooney suspended after picking up a booking against his former club Everton during the 1-0 defeat, there will be more focus on the Dutchman, who has missed the last four outings.
Van Persie has contributed seven Barclays Premier League goals and his absence has coincided with three winless domestic games since his headed goal against Arsenal before the international break last month.
"I don't know [when Robin will return]," stressed the boss. "We've been trying to get him back for a few weeks.
"But he is not ready yet. It's his groin. It's a sore groin injury and nothing desperately serious."