Boss Chris Wilder wants Jon-Paul Pittman to prove his worth at Oxford after the striker performed dismally so far this season.
Pittman arrived at the Kassam Stadium from Wycombe in the summer but has featured just six times for the Us this term, and spent three months on loan at Crawley earlier in the campaign.
Now back at his parent club, Pittman needs to show he is after a place in Wilder's first-team squad on matchdays, according to the Oxford boss.
"He's contracted to the football club, so he is part of the squad," he told BBC Radio Oxford. "If he wants to stop here then I'll be more than happy.
"It's up to him but he can be a big player for us.
"We made a decision that he needed to go out and get games, unfortunately that didn't happen at Crawley. Now he has to go out and show his qualities on the field that made us sign him in the first place."