The Dutch striker has sat out Manchester United's last four fixtures with a niggling complaint.
His last appearance came against former employers Arsenal, an encounter which saw him net the winning goal in what was billed as a crucial contest for the Red Devils.
Moyes' men have faltered in Van Persie's absence, though, taking just two points from their last three Premier League fixtures to slip 12 off the pace in the title race.
Getting Van Persie back as quickly as possible is now a top priority, especially as Wayne Rooney will sit out Saturday's home date with Newcastle United after collecting his fifth booking of the season in a 1-0 defeat to Everton on Wednesday.
Moyes, though, concedes that he is no position to speculate on whether the Holland international will be ready to face the Magies.
He told United's official website: "I don't know (when he will return). 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."