Oxford have been excellent this season, although performances have dipped recently - with one win in six games including this one.
They played well, although were not at their best, and may feel this is a game they would have won a month ago.
They let Newcastle know they were in for a battle early on when Dickie and Joelinton clashed in an aerial challenge and both players needed bandages on their heads for the majority of the game.
Watched by the largest crowd they have ever played in front of outside Wembley, they had their first ever VAR moment when the video assistant referee checked out a potential Magpies penalty for a tackle on Joelinton, but the U's escaped.
They contained Newcastle in the first half and created several match-winning chances in the second.
Marcus Browne will rue the moment he was sent in one-on-one by Alex Gorrin but shot straight at Darlow.
It could have been even better had Holland scored his first U's goal in injury time - or Dickie kept his header lower. But the Oxford owners will not complain about Newcastle heading to town for a replay in front of a full Kassam Stadium. And Robinson will fancy his chances of winning that.
Oxford United manager Karl Robinson speaking to BBC Match of the Day: "It's incredible. We've played three Premier League teams this season and only one of them has beaten us - Manchester City. So I have got to give credit to my players.
"For the fans who turned out, it just shows you this cup has got a wonderful presence. My players were exceptional. Probably say we got the best chance of the game. All in all a very good performance by my players and I am very pleased with them.
"I thought we tried to play, which was brave of the players. We started nervously and I wasn't happy. I told them to relax and once they did that they got to grips with the game a bit more."