Rochdale go into the break of their League Two encounter with Oxford United 1-0 ahead, thanks to a 44th-minute strike by Scott Hogan.
In a low-key opening 10 minutes, Michael Raynes entered the book for a late tackle on Hogan, who had got the wrong side of the defender.
In the 13th minute, Ian Henderson had the game's first shot on target, but he sent his 18-yard effort straight at Ryan Clarke.
Midway through the first half, Johnny Mullins wasted two glorious opportunities to give Oxford the lead. The defender latched onto Raynes's flick on and saw his first effort pushed away by Josh Lillis, but the 28-year-old skewed the follow up wide with the goal gaping.
Matt Done came close to giving Rochdale the lead in the 40th minute when his goal-bound strike was blocked on the line before striking both the bar and the post on its way out for a corner.
Oxford's luck ran out on the stroke of half time, though, when Hogan bundled the ball over the line from close range after Peter Vincenti's header was blocked.
