Milton Keynes Dons confirmed their place in the npower League 1 play-offs with a superb 1-0 win over automatic promotion-chasing Sheffield United courtesy if Alan Smith's first goal in five years.
The Dons, down to ten men for 25 minutes following the dismissal of Daniel Powell, only needed a point, yet they claimed three from United as Smith's first-half header proved decisive in the absorbing encounter at stadiummk.
Since switching from a striker to a midfielder Smith has been short of goals, but his first in a Dons strip ensured their second play-off campaign in as many years and strengthened their grip on fourth place.
An entertaining spectacle throughout was played out in front of the Dons' largest League gate of the season with over 15,000 fans in attendance.
With plenty resting on the game Sheffield United were backed by an incredible 6,000 travelling supporters which made for an electric atmosphere inside stadiummk as kick-off approached.
Both sides showed great intent to play the game in an easy-on-the-eye style with some neat passing ensuring every inch of the pitch enjoyed a share of the ball. There were half-chances at either end of the pitch in the opening 10 minutes when a Dons corner was nodded back across the box by Gary MacKenzie and Dean Lewington's attempt to bundle the ball over was cleared on the line by a United body.
At the other end Matthew Hill was afforded the space to race down the left flank to deliver an excellent cross into the box which was intended for Chris Porter but Lewington did well to track back and ensure the forward was unable to get on the end of it.
The Dons enjoyed a strong share of possession and when they took a second corner in quick succession the home side were looking to exploit a shaky back four. It was exactly what they did as Lewington nodded back Dean Bowditch's corner into the path of Smith, who was on hand to head the ball over the line.
Leeds-born Smith took great delight in celebrating his first goal since 2007, when he last found his name on the score sheet for Manchester United against Roma in the Champions League. The midfielder also made sure he enjoyed the chance to celebrate in front of the fans from South Yorkshire.
It was clear the goal had knocked some of the confidence out of United as passes become misplaced and shots went wayward - in particular a half-volley from Porter from 18-yards blazed well over.
The Dons were excellent on the ball and equally as impressive off it as they were quick to close down the Blades to limit their options and found holes in the United side with their pass-and-move policy.
There were some rash challenges flying in from United, possibly born out of frustration, with former Don Stephen Quinn finding his name in the referee's book for a rash challenge on Adam Chicksen. Lee Williamson and Lewington's names quickly followed after foul on the Dons skipper boiled over.
Williamson's battle with Lewington was becoming a real feisty head-to-head and when the winger got the better of the left-back United had a chance to pull level a minute before the break. Wiliamson's corner was a good one but the header from Harry Maguire was a weak one as it fell into the arms of Martin,
At the opposite end Gary MacKenzie had the opportunity to double the lead when the Dons had their own corner, but the defender's free header from Williams' delivery fell wide.
The half-time team talk clearly inspired the Blades to come out with more attacking intent and the Dons were put under pressure as they began to push forward. Quinn, who had been quiet in the first half, looked lively as he delivered a cross to the edge of the box but as Maguire tried to control the ball Gleeson was able to charge down the chance.
There was a real urgency about United yet the Dons' back four stayed strong during the storm and were given great support by the likes of Gleeson and Darren Potter.
On the hour-mark the Blades made a double substitution with Ryan Flynn and Michael O'Halloran introduced. Their first duty though was to help them defend a Lewington free-kick, however the run of MacKenzie caught out the United side and he was able to plant a thunderous free-header on the ball only for the post to deny him before the Blades defence cleared for a corner.
This time Bowitch's corner found Smith at the near post and his powerful nod looked goal-bound until Michael Doyle headed clear on the line.
With momentum swinging back in the Dons' favour they were dealt a blow in the 65th minute when Powell, booked 14 minutes earlier for unsporting behaviour, was shown his second caution for a perceived high arm on Hill.
The Dons were already lining up the chance to bring on Luke Chadwick and after going down to ten men they also brought on Jabo Ibehre to track back in defensive duties.
United were desperate to make their one-man advantage count as O'Halloran turned easily on the edge of the area to advance into the Dons box, but Williams was excellent in his timing with a fine challenge to null the threat.
A poor kick from MacKenzie created another avenue of attack for the Blades when the cross from the left was picked up by Doyle inches inside the box, but Martin stayed calm to make a comfortable save.
As United committed men forward their defence was left exposed at time and Ibehre looked to make the most of it as he powered past his marker to force a fingertip save from Steve Simonsen.
Minutes later he caught them out on the counterattack, this time breaking through from the left flank beating Simonsen his shot came off the base of the post to deny the Dons a much-deserved second goal.
It was a tense final few minutes of the game as the Blades' relentless pressure continued and when a fine cross from the right dragged across the goalmouth the Dons' hearts were in their mouths. United though, were unable to find the killer touch to find the equaliser.
A huge cheer greeted the final whistle as the Dons made sure of their top-six status.
MK Dons (4-2-3-1): Martin; Chicksen, MacKenzie, Williams, Lewington (c); Potter, Gleeson; Bowditch (O'Shea 75), Smith (Ibehre 69), Powell; MacDonald (Chadwick 69).
Subs not used: McLoughlin, Flanagan.
Booked: Lewington, Gleeson, Powell
Goal: Smith 16
Sent-off: Powell 66
Sheffield United: Simonsen, Lowton, Hoskins (O'Halloran 61), Doyle (c), Williamson, Collins, Maguire, Porter (Beattie 77), McDonald, Quinn (Flynn 61), Hill.
Subs not used: Howard, Taylor.
Booked: Quinn, Williamson
Referee: Dean Whitestone (Northamptonshire)
Attendance: 15,938 (6,135 away)
Goal-Dons Goal time: 1st goal 15.10