Peterborough boss Darren Ferguson was impressed by his squad’s mentality as they made it nine wins from the last 10 games with a 2-1 victory at Oxford to reach the FA Cup second round.

Posh made six changes, and Oxford five, for this first-round tie.

And Ferguson bravely threw on 17-year-old Ronnie Edwards to take over from his injured skipper Nathan Thompson in the first half.

But goals from Sirike Dembela, his sixth of the season, and Jack Taylor’s third goal in his last three games proved enough, with left-back Josh Ruffels on the mark for the U’s.

Ferguson said: “Mentality-wise we’re in a good place at the moment.

“We’re thinking Thompson’s injury is just a nerve and not a muscle problem at the moment.

“Obviously when it happened I had a decision to make on what to do then, and I thought Ronnie was on the bench as a defender, let’s see how he does.

“I thought he was excellent.

“Ronnie’s very good on the ball. He needs to head the ball better, but he was up against two good strikers in Matty Taylor and Sam Winnall and did really well.

“We were taking it seriously, we wanted to keep our momentum going and want to go as far as we can in the competition, so there were many motivating factors for us today, as I said to the players.

“We started ever so well, then Oxford got level, deservedly so because they had the better chances in the first half.

“But then Jack struck for his third goal from three, and then we ground it out towards the end as we needed to, so there were many pleasing aspects for me.

“Our performances were good, no-one let us down, we managed to get some game time into the ones we wanted. I’m delighted we’re into the second round.”

Dembele’s goal was controversial because he was offside when he came back to challenge Josh Ruffels, who then lost the ball.

Ferguson said: “I haven’t seen it back but have been told it’s offside. It’s a mistake from the officials so we got lucky. But Dembele still had to finish it, and he finished it well.”

Oxford boss Karl Robinson was so angry that offside was not given that he swore at the officials, and was booked.

Robinson said: “It’s offside by a long way and the assistant referee, who the managers are not allowed to speak to, said he wasn’t interfering.

“He scored a goal… that’s the most interfering you can be!

“Dembele was close enough and made a movement towards the ball, which is what put Josh Ruffels off when he was defending, and that was in the first phase. So that had to be interfering.

“And he clearly made a run for the ball. Who was that ball over the top to… it was to him, not to the assistant referee!

“But the rules have changed four or five times over the last year or so which doesn’t help.

“We also had a penalty decision that wasn’t given when Olamide Shodip was fouled that also baffles me.

“I’m furious, because I thought we played quite well. Yes, we were sloppy in different areas at times but we’ve basically been done by an offside goal and a deflection.

“My players gave a good account of themselves and gave everything in their determination and workrate.

“My grumble is that when we’re playing well we just don’t quite have that attention to detail to put the ball in the net.

“Olamide was showing some real quality in his play but two or three times couldn’t find a team-mate with his cross at the end of it, which we need to work on.”