Karl Darlow has warned Newcastle they need to develop a ruthless streak if they are to squeeze past League One Oxford into the FA Cup fifth round.

The day began with renewed hope for Newcastle fans as it emerged that owner Mike Ashley is in discussions with two different groups – one of them fronted by Amanda Staveley and boasting Crown Prince Mohammed bin Salman's Saudi Sovereign Wealth Fund among its members – over a takeover.

But Saturday ended in disappointment when the Magpies were held to a 0-0 fourth-round draw at St James' Park.

The sides will meet again at the Kassam Stadium a week on Tuesday, television schedules permitting, when keeper Darlow knows the Premier League outfit will have to be significantly better.

He told NUFC TV: "We need to be more ruthless in front of goal, we need to be as solid as possible again at the back, move the ball with better tempo and really work a lot harder than them.

"It was obviously very frustrating. I don't think we did ourselves justice in the first half in terms of how hard we've worked in recent weeks.

"But credit to them for holding their shape and not really giving us any clear-cut chances."

By head coach Steve Bruce's own admission, Newcastle huffed and puffed for long periods without ever really troubling U's keeper Simon Eastwood, and had it not been for Darlow, who produced late saves from Marcus Browne and Nathan Holland, they might have found themselves on the wrong end of a shock.

Darlow said: "Obviously they're going to get breaks when we're pushing so hard to try to win the game at home, so it was nice to be involved."

The replay will mean Newcastle's winter break will be severely curtailed, and that left Bruce scratching his head.

He said: "For me, it's a ridiculous situation that you're supposed to have a week off and then all of a sudden, they've shoved replays in there, so what's the point?"

Oxford boss Karl Robinson admitted after the game that he would rather the tie had been played to a finish on the day given the demands on his players, but left Tyneside wondering what might have been after Browne, on loan from Middlesbrough, had gone one-on-one with Darlow 20 minutes from time.

Asked if he had expected the ball to finish up in the back of the net, he said with a smile: "No, his finishing is useless.

"The worst thing about it is we trained at Hartlepool the other day and the Hartlepool manager said to me, 'what an unbelievable finisher he is!'.

"I said, 'let me tell you, if we could take your training pitch home, he'd have a chance'. It's the first time he's been brilliant with his finishing.

"He's such a talent, Browney, and Middlesbrough have got a wonderful player on their hands. He's young, though. He needs nurturing, he needs better game understanding, a better physical output out of possession and a little bit of calmness when it comes into the final third, and they are things that only age will probably give him."