Marcus Browne passed up an opportunity to dump Newcastle out of the FA Cup as League One outfit Oxford secured a deserved fourth-round replay with a 0-0 draw at St James' Park.
The on-loan Middlesbrough midfielder shot straight at Karl Darlow after finding himself one-on-one with the keeper in front of a sell-out crowd of 52,221.
Karl Robinson's men were far from overawed on an afternoon when the Magpies misfired horribly despite fielding a £81 million frontline of Joelinton, Miguel Almiron and Allan Saint-Maximin - although the Brazilian did have two goals correctly ruled out for offside.
Newcastle will have another chance to reach the fifth round for the first time since 2006, but their failure to convert home advantage will now reduce their winter break.
In an untidy start to the game, both sides were guilty of repeatedly surrendering possession tamely, and Newcastle's plans might have required a rethink had referee Rob Jones not taken a lenient view of skipper Jamaal Lascelles' ugly 10th-minute lunge at midfielder Shandon Baptiste.
Second-half goals from Grant Hanley and Josip Drmic sent Norwich into the fifth round for the first time in eight years with a 2-1 win at Burnley.
Hanley nodded home the Canaries' opener from a Mario Vrancic free-kick in the 53rd minute and Drmic struck the second four minutes later after Joe Hart palmed Lukas Rupp's attempted lob into his path.
Erik Pieters gave Burnley hope with a 72nd minute drive but there was to be no grandstand finish from Sean Dyche's men as the hangover from their midweek win at Manchester United began to kick in.
Mo Besic and Ollie Norwood provided two moments of rare class as Sheffield United ground out a 2-0 win at Millwall.
Everton loanee Besic whipped home his first Blades goal on his 13th appearance, before Norwood wrapped up the fourth-round victory amid an insipid clash at The Den.
Aiden O'Brien scuffed a glorious early chance for Millwall and the hosts never recovered, with two clinical finishes sufficient to put Chris Wilder's men in the hat for the fifth round draw.
Reading and Cardiff shared a scrappy 1-1 draw in their all-Championship tie at Madejski Stadium.
Cardiff went ahead early on through Callum Paterson but Reading equalised in the eighth minute from Yakou Meite's seventh goal of the season.
Robert Glatzel and skipper Sol Bamba missed good chances to settle it for Cardiff towards the end.
Midway through the first half, as play continued, an announcement was made over the public address system to Cardiff fans urging them to desist from alleged racist and homophobic chanting that was deemed "not acceptable".
Reading were reduced to 10 men in the 81st minute when centre back Tom McIntyre was dismissed for collecting a second yellow card.
Portsmouth progressed to the fifth round for the first time since 2010 by comprehensively beating Championship Barnsley 4-2.
Goals from Ben Close, John Marquis, Republic of Ireland international Ronan Curtis and Christian Burgess helped the home side cause an upset at Fratton Park, despite replies from Cauley Woodrow and former Pompey forward Connor Chaplin.
An unusual set of circumstances saw Coventry welcome landlords Birmingham in a fourth round tie which ended in a replay following a drab goalless draw.
The two clubs worked together to allocate both sets of fans an equal number of tickets, with a 21,193-strong crowd in attendance.
They watched a scrappy, even game which began to be edged by Coventry following the introduction of on-loan Aston Villa youngster Callum O'Hare and Sky Blues striker Max Biamou.
Leicester City advanced past Brentford in the early kick-off with a 1-0 win at Griffin Park.
Republic of Ireland Under-21 defender Dara O'Shea excelled for West Brom to help the Championship side dump a woeful West Ham out of the FA Cup fourth round at the London Stadium.
Sofiane Boufal's late leveller earned Southampton a replay against Tottenham after a 1-1 draw at St Mary's.