Assistant manager Adam Murray, a former Oxford player, came off the bench to grab a late winner a week after missing a similar opportunity to rescue a point in the opening day defeat in League Two.

Murray – one of three ex-Oxford players in the home line-up – struck two minutes from time with a 16-yard drive, nine minutes after United substitute Danny Hylton looked to have salvaged a point for the visitors with a controversial late penalty.

The goal clinched the Stags’ first points of the season on a day when everything seemed to be going against them.

First manager Paul Cox learned he would be without talisman striker Liam Hearn to a long-term knee ligament injury and then first half goalscorer Ryan Tafazolli was harshly judged to have given away a 78th minute penalty that presented Oxford with an equaliser.

Afterwards Cox said: We are down to the bare bones at the moment so it was nice to get that first win, which we thoroughly deserved.

“We have 18 fit players and three or four of those are not 100% fit, including Murray, so we are struggling for bodies.

“But they gave me everything they have got and there are some tired bodies now. I have told them that their mindset can move mountains.

“They showed an incredible amount of character to come back at the end when they could have felt sorry for themselves. That is testament to the lads. They went above and beyond what I thought they would have done.

“Adam is one of those who was not 100% fit. He is a massive part of what we are and showed the character in the squad.

“We played some good stuff, but we can improve in the final third. I was disappointed we got a bit panicky towards the end and didn’t play the simple pass and keep hold of the ball.”

The Stags shrugged off their injury concerns to dominate first half possession. They made their pressure pay six minutes before half-time. Clements’ 25-yard free kick was tipped on to the post by the diving Long and Ryan Tafazolli reacted first to dive to head the loose ball into the roof of the net from close range.

In first half injury-time Tafazolli almost added his second goal, heading another Clements free kick narrowly wide.

Oxford substitute Alex Jakubiak, making his debut on loan from Watford, twice went close to an equaliser. First his 10-yard drive was blocked in the 65th minute as the visitors dominated the second period and then the youngster wriggled clear of two defenders on the byeline and fired across the face of goal.

However, at the other end on a breakaway Clucas curled a 20-yard shot past the post as the home side tried to secure victory.

Oxford substitute Danny Hylton appeared to have rescued a first league point of the season when he won and scored a 78th minute penalty after Tafazolli was judged to have pushed him over on the byeline.

Brown almost won it for the visitors four minutes from time, but his 12-yard curling drive was beaten away by the diving Studer.

And United were punished for that miss when Murray, four minutes after coming on as a substitute, hammered a loose ball into the roof of the net to snatch victory two minutes from time after a poor clearance fell to him on the edge of the area.