Stunned by an equaliser less than a minute after the break, Oxford United went on to run riot in the second half at Histon on Saturday as they recorded their first away win of the campaign.

James Constable got off the mark for the season with a brace, and the final scoreline was sweet revenge for the club's 5-2 defeat at the Glassworld Stadium in 2008-9.

But United made it much closer than it should have been as they allowed Histon to score twice from set pieces in the last ten minutes.

It was brilliant goals from Simon Clist and Constable which set them on their way.

Clist's was the perfect instant response, after Jamie Barker had stunned the U's by equalising 55 seconds after the break.

Straight from the kick-off, Clist latched onto a defensive header 25 yards out, striking the ball very sweetly on the volley after it had bounced, and it gave goalkeeper Danny Naisbitt no chance.

Constable then made it 3-1, and it was as good as any of the 26 he bagged last season.

Green crossed from the right, Dannie Bulman chested down and Constable hit a magnificent left-foot volley from 16 yards into the top right corner of the goal.

It was to prove not to be Naisbitt's day.

Midway through the second half, he was sent off after a flare-up with Matt Green, the scorer of United's first goal.

Green tried to stop the keeper taking a quick free-kick, and Naisbitt appeared to lash out at him.

Naisbitt was given his marching orders, while Green was yellow-carded.

Substitute keeper Joe Welch also had to pick the ball out of his net, as Constable got his second after great work by Green, who crossed to him low from the right, and he just had to swivel and fire into an unguarded goal.

The impressive Green had fired the U's in front with a superb 16th-minute goal.

Jack Midson headed the ball on for Green to run onto, and as goalkeeper Danny Naisbitt rushed out, he chipped over him with a perfecftly-weighted shot.

That was Green's second of the season and crucially, from a psychological viewpoint, the first time Oxford had taken the lead in their three games at the Glassworld Stadium.

Chris Wilder had gone for an amitious three up front with last season's top scorer, Constable, supported by Midson and Green.

It was also three at centre back, with Kevin Sandwith assisting Mark Creighton and Luke Foster in trying to deal with the Stutes' aerial threat.

With Adam Murray starting on the bench, Constable was given the captain's armband.

United started the game well and Green broke free at the far post to connect with Adam Chapman's deep cross in the fifth minute, but he could only head back across goal and it was comfortably defended.

The Oxford fans had travelled to Cambridgeshire in great numbers and one became, inadvertently, involved in the action.

Histon striker Danny Wright, getting to his feet after Foster had succeeded in shepherding the ball out for a goal kick, got up and pushed over an Oxford fan who was standing by the advertising hoarding.

Whether the spectator had been goading Wright or not, the ref took a dim view of it, and booked the player.

Foster joined him in the referee's notebook for bringing down Michael Frew as he raced through on goal, Foster only saved from more serious punishment by the fact that Creighton was alongside him.

Midson dropped deeper into midfield to give United a more conventional Creighton was winning everything in the air, and ahead of him, Simon Clist and Dannie Bulman were doing a lot of good work, quickly on to any loose ball.

Histon squandered a good chance to equalise three minutes before the break when an unmarked Wright didn't properly connect with Frew's right-wing cross just eight yards out.

Damian Batt replaced Chapman for the second half, but the visitors were caught cold when Jamie Barker came in at the far post to send a looping header over Ryan Clarke and in to the net from Nat Knight-Percival's left-wing centre with just 55 seconds on the clock.

However, if United were feeling soprry for themselves they didn't show it. Straight from the kick-off, they returned to the other end and Clist sent his 25-yard volley arrowing into the goal.

As the home side put together a spell of pressure, Clarke made a good save to turn Barker's drive over the bar.

Constable almost made it 3-1 with a sharp turn and shot, but it slammed into the side-netting instead of the goal.

After he did then fire in his double, United should have seen the match ouit comfortably.

But Josh Simpson and Matthew Langston converted with headers to give them a nervous last few minutes.

Oxford Utd: Clarke; Chapman (Batt h-t), Foster, Creighton, Sandwith, Carruthers (Day 89); Bulman, Clist, Green, Constable, Midson. Subs not used: Turley, Murray, Potter.

Referee: Michael Naylor (Sheffield).