Oxford secured their place in the last 32 of the Checkatrade Trophy despite losing the longest penalty shootout in English football at Chelsea.
Elsewhere in the group stage of the new-look tournament, the development squads of Swansea, Brighton and Wolves progressed.
The group stage culminates with eight more fixtures on Wednesday night.
Group winners are guaranteed a home tie in the second-round draw, which will be made on Thursday (10:30 GMT).
U’s progress despite losing marathon shootout
Following a 1-1 draw, Chelsea keeper Bradley Collins sealed a bonus point with a 13-12 win when he saved Wes Thomas’ effort, which was the 34th spot-kick.
Chelsea defender Kurt Zouma played the full match for the Blues’ already eliminated youngsters as he continued his comeback from a long-term knee injury.
The U’s progressed alongside local rivals Swindon after the Robins secured a 1-1 draw at Exeter and then beat the Grecians on penalties.
Who else has gone through so far?
Of senior sides, Blackpool, Cheltenham, Chesterfield, Doncaster and Mansfield also made it through.
Despite not playing, Reading and Southampton’s development sides qualified because of results elsewhere, along with Bradford and Carlisle United’s senior sides.
Everton and Derby’s development squads were eliminated.
Is there a ref in the house?
Newport County appealed on Twitter for a qualified official after referee Andy Davies was injured in their tie against AFC Wimbledon at Rodney Parade.
Thankfully a volunteer was found and assumed fourth official duties for the second half.
The Exiles, who were not able to qualify for the second round, went on to beat the Dons 2-0.
Sparse attendances continue
The competition, which has been revamped by the English Football League this season, has been characterised by low attendances.
Northampton drew their lowest ever crowd of 762 for their dead rubber against West Ham’s development squad.
Already eliminated Stoke included Bojan, Peter Crouch and Giannelli Imbula in their side to face Bury, watched by 689 people.
Elsewhere 308 saw Middlesbrough’s development side lose 3-0 at home to Shrewsbury and 393 took in Barnet’s match against Peterborough.
Portsmouth’s lowest post-war crowd of 1,200 saw some early excitement as opponents Bristol Rovers substituted goalkeeper Kelle Roos after just two minutes.
His replacement Will Puddy conceded a penalty four minutes later but saved Michael Smith’s effort from the spot. Pompey went on to win 1-0 and could still reach the second round if Yeovil lose to Reading on Wednesday.
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