(Adds Moyes quote, details on injury)
MANCHESTER, England, Sept 22 (Reuters) - Manchester United striker Robin van Persie was ruled out of Sunday's derby at Manchester City with a groin strain.
The Dutchman was a surprise omission from the lineup named by manager David Moyes, who will be hoping striker Wayne Rooney will carry on his good form after scoring three goals in his last two games.
"He had a groin strain in the week, we thought he might be OK but not quite," Moyes told Sky Sports television.
"Up until this morning, we thought he had a good chance. Maybe he'll be OK for Wednesday."
United host bitter rivals Liverpool on Wednesday in the Capital One Cup, where visiting forward Luis Suarez could make a return to action after serving a 10-match ban for biting Chelsea's Branislav Ivanovic last season.
Reporting by Sonia Oxley; Editing by Justin Palmer