Chris Wilder hailed the contribution of supersubs Alfie Potter and Ryan James after they helped Oxford United to a 2-0 victory over Birmingham City at the Kassam Stadium.

Championship side Birmingham had looked in command, but the introduction of the duo on the hour turned the game in the U’s favour.

Minutes after coming on, former Derby defender James fired in the opener after Birmingham failed to clear a free-kick awarded for a foul on speedy winger Potter.

And it was James who provided the perfect cross for Potter to volley in United’s second to make it six pre- season games unbeaten.

Wilder said: “Alfie was excellent. He is doing well at the moment and he has to keep that up, as do all the players.

“The second one was an excellent team goal. We work a lot on the build-up to goals. It was a great cross in from Ryan.

“We have set high standards and there are places up for grabs, so no-one can cruise through games.

“Ryan (James) has got a lot to learn, but I’m not afraid to throw him in and give him the opportunity.”

Wilder was delighted by the way his team resisted some severe pressure from a strong Blues side.

He added: “In the first half, we were under a bit of pressure, but I was very happy with the second half.

“We were playing against some top players, but we stuck to it.”

There had been a surprise late change to the starting line-up with Andrew Whing replacing former Blues youngster Asa Hall in midfield.

But Wilder explained: “Whingy (Whing) needed a run-out, as he hadn’t played much football, so we put him in and Tommy Craddock.”

The manager said he would not be getting carried away by another terrific display from his team.

“You can’t afford to and I never do – even if we won our first ten games of the season I wouldn’t. The players have got to keep their heads down and keep working. It’s all about what happens on August 6 when we go to Rotherham.”