John Ward has drafted in Reading winger Michail Antonio on an initial month loan as cover for Ashley Vincent.
Vincent injured his knee in a tackle against Wycombe at the weekend and will undergo a scan later today.
Antonio will go straight into the U's squad to face Charlton Athletic tomorrow. The 21-year-old has found chances limited at Reading, making just two league starts in three years, and has previously had loan spells at Cheltenham Town and Southampton.