Oxford boss Wilder paid tribute to the work-rate of his players in their defeat of League Two leaders Port Vale.
Vale looked to have secured a point when Gareth Owen cancelled out Tom Craddock's strike in the first minute of time added on.
But Craddock had the final say with a last-gasp winner, much to Wilder's delight.
He said: "It was a really entertaining game and I'm delighted to get the win. When they equalised, I have to admit, I thought that was it. I thought that would be the story of the day, played well but not got the result.
"But fair play to my players, they kept going for it. And fair play to my young defenders because their front two, Justin and Marc Richards, are the best front two in the league by a million miles to my mind.
"I thought we'd just got ourselves over the finishing line and then we had two or three chances to clear it when we should really clear it and we haven't, and we've been punished for it. But we put a right shift in against the league leaders. We got after them right from the off and asked a few questions of them."