Newcastle United edged through to the last 16 of the FA Cup on a night of fireworks at St Andrew's.

In a feisty old affair, Callum Wilson was targeted by bottles from home fans, Fabian Schar ended up being slammed into the advertising hoardings and William Osula left the field after a bang to the head.

But on a pulsating night, in which Osula and Wilson were big threats, United secured their passage to round five. The victory was largely down to Joe Willock's brace as the Magpies keep hopes alive in both domestic cups.

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The atmosphere was jumping at St Andrew's, with the home fans as loud as some of Newcastle's European opponents last season. And they were soon cranking up the volume even more after a sloppy start from the Magpies.

For Birmingham grabbed the lead in the first minute after United conceded a very early corner. Kieran Dowell's corner was swung in from the right with an unmarked Keshi Anderson heading across goal for ex-Man United youngster Ethan Laird to lash home via the boot of Callum Wilson.

It was a sleepy start from Newcastle, and with the Magpies trying to pride themselves on their own set-play quality this season, they were undone easily by the routine move from Birmingham in the first 41 seconds. That was a moment that shell-shocked Newcastle and City could have been two up on 14 minutes.

It was thanks to Nick Pope that it wasn't after he got a big hand on Anderson's powerful shot in front of the away end. But Newcastle were level on 21 minutes after a great run from Wilson before the striker crossed to the back post for William Osula.

The £15million signing from Sheff United cut the ball back for Joe Willock who was on hand to force it marginally past Bailey Peacock-Farrell. The goal was awarded by the flag of linesman Nigel Lugg, who indicated to referee Matt Donoue that it had crept in.

But Newcastle wrestled control back in the game on 26 minutes after initial fine work from Osula, who cut into the final third. The ball then ended up back at the path of Sean Longstaff who slipped in Tino Livramento who crossed back in for Osula, the Dane mis-kicked but Wilson was on hand to take the sting out of the ball and put his team ahead with a cool finish.

The Blues would come back again and the tie was all square again five minutes before the break. Having failed to deal properly with Anderson's cross, Matt Targett's unconvincing header bounced straight to Tomoki Iwata.

The Japan international's vicious volley swerved dangerously through the cool winter air but Pope was never going to get close to it. The sides went in level at the break in the second city and Howe made a half-time change when bringing on Sandro Tonali for Bruno.

Howe changed things up just nine minutes into the second half with fitness levels dropping. Dan Burn, who was booked and picked up a knock, and Wilson went off for Fabian Schar and Jacob Murphy.

Play was suspended shortly after as Marc Leonard was carried off after a nasty challenge with Lewis Miley. Both sets of fans applauded as he was replaced by Willum Willumsson on 62 minutes.

Soon after the restart Schar and Jay Stansfield squared up to each other after the Swiss defender had been slammed into the advertising hoardings. The Blues star then upped the ante by suggesting he could "take" Schar "now" after he threatened revenge.

Birmingham made a treble change with 15 minutes to go as Lyndon Dykes, Alfie May and Krystian Bielik were thrown into the fray. The game boiled over a few times in the closing stages and Ben Davies was lucky to just be booked for kicking out at Osula.

Willock slipped in Murphy at the end of the 90 minutes but after steaming clean through his effort was hooked off the line by Davies. On closer inspection, Murphy would have been better squaring the ball to Osula in the middle who was poised to tap home.

The officials then displayed 12 minutes of added time following the injury to Leonard. Osula was replaced by Alexander Isak at the end after a bang in the head.

Referee: Matt Donohue (Greater Manchester)

Attendance: 27,914