Substitute James Henry headed a 90th-minute equaliser to earn Oxford a 2-2 draw against Sky Bet League One leaders Portsmouth in a game that burst into life in the second half.

Tyler Goodrham shot the U’s in front in the 45th minute, taking Marcus McGuane’s pass and firing low past goalkeeper Will Norris and into the bottom corner after a pacy break.

Colby Bishop prodded the ball home from a yard to level in the 69th minute after a scramble in Oxford’s box when grounded keeper Simon Eastwood appeared to have the ball under control but then lost it.

It was Bishop’s 15th goal of the season.

Callum Lang, making his Pompey debut after signing from Wigan just three days ago, came off the bench in the 62nd minute – and with 10 minutes to go he flicked the ball past Eastwood from 12 yards after poor defending to put John Mousinho’s team 2-1 up.

But Oxford snatched a draw which takes them back into the play-off places when Norris parried Mark Harris’ shot and Henry nodded in from close range.

Oxford boss Des Buckingham felt getting a first league win under his belt was probably more of a relief for his family than for him after the 3-0 victory over Burton.

Two goals from Ruben Rodrigues and one from Marcus McGuane earned the U’s a comfortable victory and the scoreline could have been double that.

Former Oxford goalkeeper Max Crocombe pulled off a string of saves to keep the score down, and Burton also cleared four attempts off the line in one crazy 10-second spell.

Oxford-born Buckingham said: “I think it’s a relief for my dad and my family.

“The first people that speak to me are my family and my friends… I don’t need reminding from anyone else.

“This week we set up to do something and I started to change things and put more of a stamp on what we are doing.

“The players have been excellent in training this week and I’m extremely pleased with what I have seen today.

“We prepared ourselves as well as we could and I don’t think Burton had a shot on goal.

“With the exception of Max Crocombe in their goal, who I thought had a wonderful game, we could have had a couple more as well.

“I worked with Max when he was the youth-team keeper here – it’s the third time I’ve bumped into him, we also crossed paths in Australia and New Zealand.

“He’s obviously disappointed with the result but I’ve just said to him ‘you can’t be disappointed with that performance you’ve put in’.

“I think they cleared four off the line in the space of 10 seconds. And we hit the post just before that.

“The most important thing is that you keep the control and keep doing what’s got you the opportunities – and that’s what we kept doing.

“It took a very good strike from Ruben for the second, and then it was a wonderful strike from Marcus for the third.

“The work rate that our wingers put in is phenomenal, not just in going forward but in getting back.”

Harris was twice thwarted by Crocombe, but also missed other opportunities.

“The goals will come for Mark Harris,” added Buckingham. “The way we’ve set the team up he’ll get chances.

“He had two wonderful chances today and their keeper’s made great saves. As long as he continues doing what he’s doing, the goals will come – and when they do they’ll be like London buses.”

Burton’s caretaker boss Gary Mills said: “We asked the lads to give everything and I’m really proud of them. They worked really hard and showed real character.

“We wanted them to go out there, enjoy it and show bravery. In patches they showed some decent stuff and the blocks they put in showed real commitment.

“After the match, I thanked the lads for their efforts. I was concerned that Oxford had so many opportunities – they got into our final third too much.

“We didn’t close the ball down enough from a deep line. But they were quality finishes and Oxford are a good side – there’s no doubt about that.

“They’re a big club with big resources and a really good squad. They’ll be challenging.

“We didn’t work the Oxford goalkeeper enough. But this is the start of a journey and while we’re in charge we’ll try and get more players in attacking areas on the pitch with more crosses and more shots.”

Mills has taken temporary charge from Dino Maamria, who departed in the week.

Mills added: “I don’t know how long we’ll be in charge but we’ll try and deliver something that is attacking and enjoyable to watch – something to get the crowd off their seats. But it’s not going to happen for us overnight.”

Des Buckingham enjoyed a first win as Oxford manager as the League One side reached the third round by beating League Two opponents Grimsby 2-0.

The Mariners were unable to repeat last season’s cup exploits when they became the first club in the competition’s history to knock out five teams from higher divisions on their way to the quarter-finals.

Marcus McGuane fired Oxford ahead in the 11th minute and Billy Bodin got the second 15 minutes from time.

Grimsby were the architects of their own downfall as Oxford’s opener came from their own corner. Josh Murphy raced 60 yards and although Harvey Cartwright parried his drive, McGuane followed up to score.

Otis Khan had two half-chances for Grimsby in the first half and with 20 minutes to go Donovan Wilson was denied by James Beadle’s low save.

Cartwright was much the busier, saving from Stan Mills, twice, and Ruben Rodrigues. The visiting keeper also saved superbly from Bodin and Tyler Goodrham’s drive.

But he could do nothing to stop Bodin nodding in Cameron Brannagan’s chipped cross in the 75th minute to seal Oxford’s progress.

Wycombe boss Matt Bloomfield believes the 2-2 draw at Oxford confirmed what a good team he has after a week of three tough matches for the club.

He felt the Chairboys probably deserved more than just two points from their fixtures against Peterborough, Bolton and Oxford.

A dramatic clash between local rivals at the Kassam Stadium featured three second-half penalties.

Luke Leahy converted two for Wycombe after Marcus McGuane unluckily slipped and handled the ball, then when James Beadle brought down Brandon Hanlon.

Oxford, who had taken a 25th-minute lead through Ruben Rodrigues, snatched a point deep into stoppage time as sub Cameron Branagan converted from the spot when Leahy tripped Mark Harris.

Bloomfield was not prepared to criticise Leahy, a summer signing from Shrewsbury, for conceding the late spot kick.

Bloomfield said: “Luke is so disappointed in the dressing room but I’ve said to him to get his head up.

“To take that responsibility and have that calmness and surety – and especially with the second penalty to be able to repeat it again on what was a big occasion for our supporters and ourselves – is tremendous.

“Luke has been an unbelievable signing for us – both as a player and his influence as a leader and as someone who can contribute at both ends of the pitch.

“I’m really pleased that we’ve got him at our football club.”

Bloomfield added: “We wanted to come to Oxford and press and impose ourselves and we did that.

“It changed the balance of the game when Oxford scored and they then had a 10-minute spell where we had to hang on a bit.

“I thought Oxford’s penalty at the end was a bit soft. But it’s not easy for the referee in that situation with so much emotion in the stadium.

“We wanted to be on the front foot and play in attacking areas. I’m so proud of my players.

“We’ve played three top teams this week and we’ve been the better team in the second half in each of them.

“We’ve come away to top sides that have started the season well and we’ve shown that we’re a good team.”

Oxford boss Liam Manning was shown the red card for angry comments when Wycombe were awarded their second spot kick.

Under Football League rules he was not allowed to talk to the media after the match.

U’s assistant head coach Chris Hogg said: “It was a topsy-turvy affair. We’ll take a point at the end of the game and we were really happy with some of the play from the boys.

“And credit to the boys for the energy and attitude in getting back into it.

“But I think in general it’s quite sad now that, at every level we’re having to talk about key decisions rather than the football that was played.

“Both sets of players probably feel aggrieved at the end.”

Hogg felt it was important to have key midfielder Brannagan back in the fold after he had missed two games with illness.

“It’s been great to have Cameron back in the building again – he’s only been back in for a couple of days – and they were important minutes for him today.

“One thing you know about Cam is his enthusiasm and personality is big for the group, and big for the club.

“He’s definitely lifted the place the last 48 hours. I never had any doubt when he stepped up for that penalty – I had full faith in him that he’d score.”