With the contest heading towards a stalemate, Stephenson netted a dramatic winner in the closing stages, the striker's 14th goal of the season in all competitions at under-23 level, after drilling the ball home.

Birmingham were then reduced to ten men in stoppage-time as Jordan James received a straight red card for dissent before United's second-string held firm to seal maximum points, moving into third place of Division Two.

Elliott Dickman made four changes to the side which suffered a 2-0 Premier League Cup defeat against Fulham as Santiago Muñoz made his home debut for United's under-23 side while Adam Wilson, Joe Oliver and Trialist were all named in the starting line-up.

Newcastle had already met their Blues counterparts three times this term, with the young Magpies boasting a 100 per cent record ahead of the Premier League 2 encounter on Tyneside after two Premier League Cup victories as well as a 4-0 away win in August.

Oliver, who signed his maiden professional contract with the Magpies last summer, went close to registering his first goal at under-23 level. Following a dangerous attacking move, the teenage right-back cut inside before directing the ball over the crossbar.

Stephenson was unfortunate not to score a fourth goal in as many games against the Blues after the Blyth-born forward raced onto Muñoz's pass before rounding City goalkeeper Oli Basey but saw his resulting shot blocked by the recovering defender Rico Browne.

Newcastle were left appealing for a red card after Stephenson latched onto Charlie Wiggett's lofted pass before flicking the ball beyond the rushing Basey, who brought down the United striker but referee Garreth Rhodes only brandished a yellow card to the Birmingham shot-stopper.

Muñoz, who joined the Magpies on an 18-month loan from Santos Laguna in August, almost sent the Magpies into the lead as the Mexican striker, an Under-17 World Cup finalist in 2019, cleverly controlled Stephenson's low cross but his strike towards goal was tipped around the post by Basey.

Newcastle goalkeeper Jake Turner, who spent the first-half of the 2021/22 campaign on loan at League Two Colchester United, prevented the hosts from trailing at the break as the 23-year-old held Tate Campbell's low drive from 25 yards.

Niall Brookwell, who scored in United's Premier League Cup win away at Birmingham in January, went close to netting his first league goal of the season after combining with Stephenson but the Wigan-born midfielder's strike towards goal was blocked by Browne.

Jay Turner-Cooke, who joined the Magpies' youth set-up from Sunderland in January 2021, went close to notching his ninth goal of the season at second-string level as the 18-year-old's vicious drive from distance flew narrowly over the bar.

The hosts continued their push for a breakthrough as Wilson controlled Turner-Cooke's diagonal pass before driving into the box but the left winger's powerful effort was beaten away by Basey.

In the 89th minute, Newcastle took the lead through Stephenson's impressive strike. After racing onto Brad Cross' lofted pass, the 19-year-old forward drilled a ferocious shot beyond Basey.

With the full-time whistle approaching, Birmingham were reduced to ten men as James was sent off for swearing at the referee.

Newcastle United Under-23s face an away trip to Stoke City in their upcoming Premier League 2 fixture, which will take place at the bet365 Stadium on Monday, 21st March (kick-off 7pm GMT). 

Newcastle United Under-23s: Jake Turner, Joe Oliver, Charlie Wiggett, Brad Cross, Josh Scott, Niall Brookwell (c), Jay Turner-Cooke, Trialist (Nathan Carlyon 73), Adam Wilson, Santiago Muñoz (Isaac Westendorf 61), Dylan Stephenson.

Subs not used: Harry Barclay, Will Brown, Ellis Stanton.