Oxford United were taken to a replay by Barrow after having Luke Foster sent off near the end of the first half.
But they will still be in the hat for the third-round draw on Sunday after this hard-fought second-round encounter at the Kassam Stadium.
The replay will be at Holker Street on Tuesday, December 8 (7.45).
Jamie Cook gave United a ninth-minute lead when he cut in from the right and his low left-footed shot deflected off defender Mike Pearson to wrongfoot goalkeeper Stuart Tomlinson.
Chris Wilder had rung the changes, bringing in five players who did not start the 1-0 win at Forest Green on Tuesday.
Top scorer James Constable, who had suffered a knock on his back, was named as one of the subs, giving Jack Midson the opposrtunity to start as the target man.
lfie Potter and Jamie Cook came in to operate either side in attack, giving the team plenty of width, and there were changes in the fullback positions as well, with Adam Chapman and Steven Kinniburgh coming in.
Barrow made an eneterprising start, indicating that they were going to give it a real go, and Marc Goodfellow, signed on loan from Burton, was heavily involved in their early raids.
In the opening minute, though, United went close. Potter darted up the right, Cook crossed and, arriving at the far post, Simon Clist was unable to nod it in under challenge from a defender purely because of his lack of height.
Goodfellow then had a shot blocked, and followed up with a low left-footed effort that Ryan Clarke saved by his near post.
And it needed a strong blocking challenge by Luke Foster to prevent Goodfellow converting when Andy Bond got free down the right to send in a telling cross.
Cook's goal helped the home team's confidence, and they began passing well. Chapman made an excellent overlapping break but, as when Midson got behind the Barrow defence, either nothing came of it or the end product was missing.
Potter, released by a fine pass from Midson in the 17th minute, cut inside menacingly from the left touchline and was unlucky to see his shot deflect wide.
And the former Havant & Waterlooville FA Cup star was not far away with a shot on the turn that Tomlinson spilled.
At the other end, though, United always had to be wary, however. Andy Bond managed to nip in for a header after Greg Blundell got in behind their defence to send over a centre from the left bye-line.
And with half-time approaching, disaster struck.
Robin Hulbert got goalside of Foster as he raced in on goal, and the ref spotted a push in the back by the U's defender, and pointed to the spot.
It clearly was a goalscoring opportunity, so there was no surpriuse then when the red card came out.
Andy Bond converted the penalty into the bottom left corner to equalise.
A few moments later, the unlucky Potter was sacrificed as Wilder sent on Ross Perry and the home side'a formation effectively became 4-3-2.
The first half ended with Mark Creighton sending an exocet of a volley from 20 yards whistling over the bar.
Kinniburgh produced a vital block at the start of the second half when Barrow pressed.
The Oxford fans raised the volume to try to lift the team, but with a man short, it was hard going, and the visitors were defending for their lives.
Midson got around Barrow's defence again, yet his cross was just beyond the reach of Chapman, coming in from deep beyond the back post.
With 17 minutes remaining, Damian Batt replaced Kinniburgh, who had taken a knock, and Capman pushed up into midfield, with Clist dropping to left back.
Yet it was the Bluebirds who might have struck again, on the break. Bond beat the offside trap, Clarke hesitated in coming but then did well to check to avoid bringing him down, and Bond scooped his shot from a difficult angle onto the roof of the net.
Midson headed narrowly wide in the last minute, but that winning goal just wouldn't come.
Oxford Utd: Clarke, Chapman, Foster, Creighton, Kinniburgh (Batt 73), Bulman, Murray (Deering 90), Clist, Potter (Perry 44), Midson, Cook. Subs not used: Turley, Sandwith, Co,nstable, Day.
Sent off: Foster.
Booked: Clist Referee: Jock Waugh (Sheffield) Att: 6,082 (390 from Barrow).
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