Lewis left cursing luck
Oxford caretaker manager Mickey Lewis says luck deserted his side for Cheltenham's late leveller in the 1-1 draw.
Jamie Cureton levelled in the 84th minute as he deflected home fellow substitute Zack Kotwica's shot.
Oxford had gone in front in the 78th minute through Australian winger Ryan Williams, who drilled in a low shot from 15 yards.
But the U's have now gone five games without a win and their hopes of taking one of the three automatic promotion places are receding.
Lewis said: "I don't think we had a lot of luck. Their goal hit the lad on the floor and looped up and in.
"We should have won that game but I was delighted with the performance. We were on the front foot throughout.
"It's a tough league and you only need to look at the league table to see that. When you see the results elsewhere, it's all draws."
For Williams, it was a second goal in two games after he found the net against Burton on Saturday.
Lewis added: "Ryan's playing his heart out for us. He's a real threat going forward and he took his goal well.
"James Constable had a lot of chances, coming in from the left of midfield, and I was happy with the two that came into midfield, Johnny Mullins and Josh Ruffels, who made it solid in there."