Allan Saint-Maximin's stunning solo effort in extra-time saw Newcastle United reach the fifth round of the FA Cup for the first time under Mike Ashley.
Story of the game
Sean Longstaff opened the scoring after just 15 minutes.
Joelinton doubled the visitor's on the half-hour mark.
Liam Kelly got one back for Oxford United in the 84th minute.
Nathan Holland levelled things up in the final minute of added time.
Saint-Maximin put the Magpies ahead in the 116th minute.
The first chance of the game resulted in the opening goal as Matt Ritchie found Joelinton in the box who set up Longstaff on the edge of the area before firing high into the net.
Longstaff took his time on the edge of the area taking a few touches forcing the Oxford players to dive in before firing into the roof of the net.
After winning the ball on their own box Longstaff pinged a ball over the top to Joelinton who took one touch before curling an effort into the bottom corner.
Two minutes later Jamie Mackie took a touch inside the box and set himself up for a volley from six-yards which was saved expertly by Karl Darlow.
They recycled the ball before Nathan Holland picked out Sam Long who smashed a shot past Darlow only for Jamaal Lascelles to head away off the line.
During a poor second half Holland out muscled Fabian Schar with 15 minutes left to play before whipping in a dangerous cross for Matty Taylor who could only poke his shot wide.
After Ritchie gave away a needless free-kick Kelly curled one beyond Darlow from 25-yards out.
Longstaff scuffed a shot wide after 89 minutes when Saint-Maximin pulled it back for him only 10-yards out but could only see his shot drift aimlessly wide.
In added time Josh Ruffles found space inside the box but saw his shot sliced over the bar when he had most of the goal to aim at.
After Newcastle failed to clear a free-kick the ball fell to Holland on the edge of the box who curled a superb volley into the far corner.
Within 50 seconds of first-half extra time, Holland forced Darlow to palm a cross straight into Dan Ageyji path who had an open net but Ritchie slid in to deny a certain goal.
In the final minute of first-half extra time, Saint-Maximin beat two defenders in the box before racing through on goal but saw his shot stopped by Simon Eastwood's knee.
Matty Longstaff almost curled one into the top corner from the edge of the area after just 40 seconds in the second half of extra time.
Saint-Maximin picked the ball up near the halfway line and ran at the Oxford defence before dancing three defenders and unleashing a thunderbolt into the far corner.
Newcastle continue to defy logic
The Magpies played the majority of the game as well as all of extra time without a striker and Steve Bruce brought a defender on when they were chasing the game.
However, just like so many times this season they fond a way to win and did it with two stupendous goals from midfielders.