Charlton Athletic manager Nathan Jones has challenged his side to produce "one more big performance" after the 2-1 defeat to Ipswich Town.
The Addicks still need another point to guarantee Championship survival - or for Oxford to fail to win both of their final two games.
"I'm really frustrated. I thought the overall performance was good, I thought we were aggressive, we were front-footed, started brilliantly," Jones told BBC Radio London.
"We were disjointed because of the injuries. Losing Amari'i [Bell] caused us to reshuffle. Then we lost TC [Tyreece Campbell] at half-time. Then we made changes and all those things conspired against us.
"And then we give a cheap foul away for the penalty. You can't afford to do that to good teams because they punish you. It's a cheap one and that's what's costing us at the minute.
"We need to do the basics better and to make sure we put in one [more] big performance."
