Tony Capaldi's Oxford debut will not come this weekend against Bradford as a back injury continues to keep the defender out.
The former Northern Ireland international left-back arrived from Morecambe on a free but has missed the first two games, both of which resulted in losses for the Us.
Striker Tom Craddock will join Capaldi on the sidelines and is also yet to feature this term. Craddock, who struck 13 goals in last season's League Two campaign, continues to be hampered by a knee injury.
But boss Chris Wilder could welcome back local boy Paul McLaren after the midfielder missed the first two games.
Oxford took Cardiff to extra time in the Carling Cup on Wednesday with a largely unchanged side from their opening-day defeat to Rotherham.
Bradford pair David Syers and Steve Williams are both doubtful.
Midfielder Syers damaged his medial knee ligament in the midweek Carling Cup defeat at Leeds and will have a scan, while centre-back Williams has suffered a recurrence of the thigh strain that hindered him during the close season.
Manager Peter Jackson is expected to hand a starting place to Ritchie Jones, a free summer signing from Oldham who has recovered from a calf problem, should Syers fail to make it.
Defender Luke Oliver, fit again following a foot injury, could make his first appearance of the season if Williams is ruled out.
Otherwise, Jackson has no new injury concerns and is not expected to make too many changes after his side turned in an impressive display against Leeds, with on-loan Tottenham goalkeeper Oscar Jansson expected to retain his place.
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