Match ends, Oxford United 3, Newcastle United 0.
League One side Oxford reached the FA Cup fifth round for the first time in 23 years with an impressive victory over Championship promotion chasers Newcastle United.
Kane Hemmings met a Chey Dunkley back-post header to put Oxford ahead.
Aleksandar Mitrovic missed the chance to level when his penalty was saved low down by Simon Eastwood.
Curtis Nelson added a second Oxford goal from a Rob Hall corner before Toni Martinez made it 3-0 from a Hall cross.
- BBC One is showing two live FA Cup ties on Sunday. Millwall host Watford at 12:00 GMT, followed at 16:00 GMT by holders Manchester United against Wigan.
Newcastle have not progressed beyond the fourth round since 2006, the season their manager Rafael Benitez led Liverpool to victory in the final against West Ham.
Benitez made nine changes to his starting line-up with Isaac Hayden and Ayoze Perez the only starters from their previous league game against Rotherham.
One of those changes, striker Mitrovic, spurned their clearest chances even before his second-half spot-kick was saved.
He was twice denied by the legs of Eastwood in the first half when in on goal and then failed to convert from 12 yards after Phil Edwards brought him down as he surged into the area.
Oxford, in their first season back in League One and their second successive year in the fourth round, were more than worthy of victory.
Martinez, who arrived on loan from West Ham on Monday, capped off a fine performance with the third goal after he came off the bench.
For Hemmings, the opening goal against a side 35 places above Oxford on the Football League ladder was his fifth in the Cup this season, having now scored in each round of the competition proper.
Oxford United manager Michael Appleton told BBC Radio Oxford:
"I was delighted with how the players started the game. I thought we got a foothold in the game in the first half and they showed the quality they've got in the first half, while Simon Eastwood had to make two very good saves towards the interval.
"I said to the players at half-time that they wouldn't get a better opportunity to get into the last 16 of the FA Cup. I said that we'd need to keep our concentration and that Simon would have to make one more important save, thankfully he did that with the penalty.
"I thought we'd scored the first goal too soon and for 15 to 20 minutes, they pinned us in a little bit. But, the players rode the storm and I think the penalty save gave everyone a lift.
"I think that belief really told in the last 15 minutes and I thought the players were magnificent."
Newcastle United manager Rafael Benitez:
"We didn't underestimate Oxford - we didn't take our chances in the first half, we missed a penalty and Oxford took their chances.
"You have to give credit to them as they were fighting for the result and we just made too many mistakes and paid for the first one at the start of the second half.
"I feel sorry for the fans and for us, as we wanted to go through and we could've done on the chances created in the first half. It's something we need to analyse and find out why we made the mistakes we did and be ready for the next game."
- 16EdwardsBooked at 66mins
- 10MaguireSubstituted forMartínezat 70'minutes
- 15HemmingsBooked at 57minsSubstituted forSercombeat 83'minutes
- 5HanleyBooked at 90mins
- 19HaidaraSubstituted forRitchieat 77'minutes
- 36Ben El-MhanniSubstituted forGouffranat 68'minutes
- David Coote
- Shots on Target
Second Half ends, Oxford United 3, Newcastle United 0.
Corner, Oxford United. Conceded by Jesús Gámez.
Foul by Jesús Gámez (Newcastle United).
Marvin Johnson (Oxford United) wins a free kick on the left wing.
Delay over. They are ready to continue.
Delay in match Ryan Ledson (Oxford United) because of an injury.
Grant Hanley (Newcastle United) is shown the yellow card for a bad foul.
Foul by Grant Hanley (Newcastle United).
Antonio Martínez (Oxford United) wins a free kick in the attacking half.
Grant Hanley (Newcastle United) wins a free kick in the defensive half.
Foul by Antonio Martínez (Oxford United).
Attempt missed. Aleksandar Mitrovic (Newcastle United) right footed shot from outside the box misses to the right. Assisted by Yoan Gouffran.
Curtis Good (Newcastle United) wins a free kick in the defensive half.
Foul by Robert Hall (Oxford United).
Goal! Oxford United 3, Newcastle United 0. Antonio Martínez (Oxford United) header from the centre of the box to the bottom left corner. Assisted by Robert Hall with a cross following a corner.
Corner, Oxford United. Conceded by Grant Hanley.
Substitution, Oxford United. Liam Sercombe replaces Kane Hemmings.
Goal! Oxford United 2, Newcastle United 0. Curtis Nelson (Oxford United) header from the centre of the box to the bottom right corner. Assisted by Robert Hall with a cross following a corner.
Corner, Oxford United. Conceded by Curtis Good.