Former Sheffield United midfielder Louis Reed scored twice against his boyhood club as League One Mansfield Town stunned the Blades in a thrilling seven-goal FA Cup third-round tie.

Two excellent strikes from Reed before half-time, either side of Gus Hamer's beautiful dipping strike from 20 yards, gave the Stags a deserved 2-1 lead at the break against their Championship opponents.

Buoyed on by approximately 5,000 visiting supporters, Mansfield raced into a three-goal lead soon after the interval through Lucas Akins and Rhys Oates.

But a goal from Blades substitute Patrick Bamford, as well as an own goal from Mansfield's Nathan Moriah-Welsh, meant the Stags had a nervy final 25 minutes to see out.

United heaped on the pressure in the final stages as they searched for an equaliser but the visitors saw out the match to claim a famous win and clinch a fourth victory on the bounce in all competitions.

Reed returned to Sheffield United where he began his career and was handed his debut as a 16-year-old - becoming the club's youngest ever appearance-maker in the league - by now Stags boss Nigel Clough.

"Back where it all began, bit of a bitter-sweet moment obviously because it's against the team I support but what a result for all those fans behind the goal, and the team," Reed told BBC Radio Nottingham.

"I just said to [Rhys] Oatesy then, in the warm-up, I think it's one of the worst performances I've had in the shooting drill before but I suppose if you use them up there, they don't come out in the game.

"I've not come up with many goals while I've been here so two is just brilliant. I think the first one is better, the second one took a bit of a deflection, but I'm still claiming it."

It was the home side that raced out of the traps, and in just the second minute, Hamer fired a warning shot from outside the box which just missed the top corner.

Mansfield posed a threat on the counter-attack throughout and Oates twisted Blades defender Ben Mee inside and out before hitting a rasping left-footed drive which was brilliantly kept out by stand-in United keeper Adam Davies.

After the resulting corner was only partially dealt with, Reed opened the scoring with a stunning hit from well outside the area, finding the top corner and leaving Davies grasping at thin air.

Mansfield's lead lasted just seven minutes, however, when Hamer found a pocket of space outside the box and unleashed an equally sumptuous strike into the top corner for the Blades.

Not to be outdone, Reed then volleyed Town back in front moments before half-time after another corner fell invitingly to him, with his effort taking a deflection off Blades captain Oliver Arblaster before hitting the back of the net.

In a devastating counter-attack, Mansfield extended their lead five minutes after half-time when Oates raced down the right hand side before pulling the ball back to Akins who provided the perfect finish, burying the opportunity into the far corner.

Oates remained a constant thorn in the United defence and, after he got the better of Mee once more, he beat on-rushing Davies at his near post to score his fourth goal in three games.

At that stage, the tie looked like it had effectively been wrapped up, but United hit back with two quick fire goals of their own.

First, Bamford - who signed a new 18-month deal with United ahead of the match - capitalising on some statuesque defending from Mansfield to prod home from a corner to reduce the deficit to two.

Then, a dangerous cross from Andre Brooks was flicked inadvertently by Stags winger Moriah-Welsh into his own net, via the crossbar, leaving Mansfield keeper Liam Roberts no chance.

In the final stages, Harrison Burrows hit a shot from the edge of the box but it was beaten out well by Roberts as momentum continued to shift in the hosts' favour.

With five minutes remaining, the ball ricocheted kindly into the path of Tyrese Campbell - who looked destined to equalise - but his effort was brilliantly blocked by Stags skipper Ryan Sweeney as the visitors held on to win an instant FA Cup classic.

Sheffield United boss Chris Wilder told BBC Radio Sheffield after making 10 changes to the starting line-up that beat Leicester City in the Championship on New Year's Day:

"Incredibly disappointed. I said I think the players might be a little bit bored of me going after them – this was an opportunity.

"I picked a team today to win a game of football, the changes that we made, we had to make. I'm not resting anybody - that team I picked, should have been good enough to win.

"I feel sorry for Adam Davies. The goals that we conceded are ridiculous. The centre forward has dominated the two defenders all afternoon.

"Today was an opportunity for people to stick themselves right in front of me and go, 'why aren't I playing?'.

"[Andre] Brooks just played where he wanted to play, Femi [Seriki] didn't do what he needed to do. Pat [Bamford] came on and made a big difference."

Mansfield boss Nigel Clough told BBC Radio Nottingham:

"Another memorable victory and another great occasion for our incredible supporters.

"Not just to come to a top, top Championship team, but to score four goals as well - brilliant.

"Louis Reed – two brilliant strikes from the edge of the box – it's about your first touch and make sure you hit the target and he did that twice.

"The quality they're bringing on is Premier League quality. The likes of Patrick Bamford. The only disappointing thing is when you go 4-1 up, the second and third goals we concede are very poor from our point of view but it's difficult to be too critical.

"One of the highlights for us was the four goals that we did score, all of them were brilliant goals."