James Ward-Prowse’s penalty six minutes into stoppage-time rescued a point for Southampton in a remarkable finish at St James’ Park.
Referee Paul Tierney awarded the spot-kick after Adam Armstrong was adjudged to have been fouled in trying to equalise against his former club.
Saints must have thought they were beaten when Allan Saint-Maximin pounced in the 90th minute for the hosts, who were outplayed for long periods – particularly in the first half.
Newcastle had taken the lead 10 minutes after the interval through Callum Wilson, before Mohamed Elyounoussi’s fourth goal in four days levelled things up on 74 minutes.
Ralph Hasenhüttl made his first Premier League changes of the season, having kept the same starting line-up in the opening two matches against Everton and Manchester United.
Elyounoussi’s reward for scoring a hat-trick in Saints’ club-record away win, 8-0 at Newport, was a first Premier League start since May 2019.
Kyle Walker-Peters, also on target at Rodney Parade, kept his place at left-back, with Romain Perraud and Theo Walcott dropping to the bench.
Saints, sporting their new yellow and blue away kit for the first time in a competitive game, settled well.
Walker-Peters and Armstrong, who was eager to impress on his return to St James’ Park, scuffed early warning shots, but the intent was there from the visitors to get on the front foot.
Ché Adams was the first to test goalkeeper Freddie Woodman, albeit the ensuing save was routine, before a really slick piece of football on the touchline released the energetic Tino Livramento for the first time, whose cutback was steered wide by Ward-Prowse, who would have preferred the chance to fall to his right foot rather than his left.
Fans were back inside this cavernous stadium but it was not helping the home team, whose natives were losing patience as Saints seemingly pushed and probed at will.
But the breakthrough was not forthcoming, even in spite of a glorious chance for Djenepo midway inside the first half.
The ball dropped fortuitously the way of Livramento via a Newcastle boot, meaning the full-back could not be ruled offside, prompting a square pass across goal for Djenepo, who somehow scooped the ball over from no more than four yards.
The winger was in the thick of it again with another chance in the six-yard box soon after, but his shot was blocked with Adams in support.
The Geordies were fed up, to put it bluntly, but their jeers turned to roars of encouragement when Jacob Murphy went close with a free-kick from a rare attack.
It would prove only a temporary breather for the home defence, who were under pressure again when Adams showed admirable persistence to close down three Newcastle players, eventually reclaim possession and feed Elyounoussi, who was losing balance as he went to shoot and could not generate sufficient power to beat Woodman.
However poor the hosts had been, they still had two things in their favour: firstly, they were still level; secondly, they possess a constant counter-attacking threat in the shape of Saint-Maximin and Wilson.
The pair hardly touched the ball for 40 minutes, but combined to produce Newcastle’s best moment when the Frenchman outran Ward-Prowse to tee up the striker, whose shot was high and wide from 20 yards.
At last Newcastle had a sense of purpose, and Wilson forced an important save from McCarthy with a near-post header from a corner that might have snatched a half-time lead for the team that had been thoroughly second best.
The only thing missing from Saints’ point of view was a goal, which Djenepo threatened to provide soon after the restart, whipping a shot towards the far corner that was beyond the reach of Woodman but did not quite curl enough to nestle inside his left-hand post.
Instead it was Newcastle who edged in front 10 minutes into the second half, as Saints were made to rue missed chances.
Murphy met a deep cross with a header back across goal for Wilson, who threw himself in where it hurts to score from close range, reacting quickest to break the deadlock against the run of play.
Hasenhüttl introduced Redmond and Armando Broja – the latter for his Premier League debut – in a bid to regain the momentum, and the plan worked as Redmond provided the assist for the in-form Elyounoussi, who attacked the far post in similar fashion to Wilson, forcing the ball past Woodman.
Saints were the team in the ascendancy attempting to win the game thereafter, but Saint-Maximin must have thought he’d snatched it only for Ward-Prowse to hold his nerve from the spot after a lengthy delay added to the drama in a tension-filled St James’ Park.