Mario Lemina had given the hosts the lead after rounding off a free-flowing counter-attack late in the first half, sweeping home after a clever dummy from Joao Gomes.

Newcastle had earlier struck the post through Anthony Gordon, but Eddie Howe's men struggled to carve out any clear-cut chances before a series of half-time changes prompted an improvement.

Schar’s deflected strike levelled the scores with 15 minutes to play, then substitute Barnes went one better by curling a stunning effort beyond Sam Johnstone to secure the triumph.

The result keeps Wolves in the bottom three with just a single point, while Newcastle moves up to third with 10, ahead of its meeting with Fulham next week.

With rumours of unrest behind the scenes at St. James' Park circulating, Howe acknowledged the magnitude of the triumph as his side aims to return to the UEFA Champions League places this year.

"Massive win for us. Away from home, we have questions to answer and that is a big step forward for us," Howe said.

"I think we are stepping forward in terms of our performances. I think it was a step in the right direction.

"We can improve in lots of different aspects and that is what we are going to be working on this week. We are a really tight-knit group and we have to remain that way."

The shift in momentum came after the break, when Howe made three changes to try and alter his side's fortunes.

Alexander Isak and Sean Longstaff were among those to be replaced, making way for goalscorer Barnes and Sandro Tonali, with the Magpies head coach detailing the reasons behind his decision. 

"I wasn't totally satisfied and the lads know they have to perform. We have the ability to make those changes," Howe said.

"I have to credit the players who came on. Everyone played their part and it is a massive win.

"I got the sense [of urgency] at the start of the half and then there was bit of a lull and Fabian's goal injected confidence.

"It took a moment of real class from Harvey and then we had cramp and all of those battling qualities at the end to get over the line."

With 10 points after four games, Newcastle has made its best start to a Premier League campaign since the 1995-1996 season, when it won each of its opening four matches under Kevin Keegan.

But the afternoon belonged to Schar and Barnes, with the Magpies scoring two goals from outside the box in the same Premier League game for the first time since April 2018 against Leicester City (Ayoze Perez and Jonjo Shelvey).

Barnes has now been directly involved in 11 goals in his 25 Premier League appearances for Newcastle (seven goals and four assists), averaging a goal or assist every 87 minutes of league action for the Magpies.

Schar's strike from distance saw him net his fourth goal from outside the box since his Newcastle debut in 2018, more than any centre back in the competition.