Charlton fell to a first defeat in seven league games after a remarkable contest at Glanford Park.
Scunthorpe had led early on through Charlie Goode, but the game was soon turned on its head as Lyle Taylor and Joe Aribo struck back for the Addicks.
Cameron Borthwick-Jackson’s double had the Iron ahead once again before the interval, before Aribo’s second of the game midway through the second-period hauled his side back onto level terms.
Parity didn’t last long though, with Josh Morris successful from the penalty spot moments later. Stephen Humphrys added a fifth deep into injury-time to sentence Lee Bowyer’s side to a first reverse since the 1-0 home loss against Peterborough in August.
The South Londoners were off the worst possible start as they fell behind with just three minutes on the clock. Ryan Coclough had seen a free-kick deflect wide but Goode was on-hand to poke the resulting corner home at the near-post.
It went from bad to worse as Bowyer lost left-back Lewis Page to injury. The former West Ham man had been suffering with a groin problem over the last few weeks and was replaced by youngster Anfernee Dijksteel, who went to right-back, with Chris Solly coming across to the left-hand side to fill the void.
Taylor nearly levelled up for the visitors as his cross-shot curled just wide of the far-post, with Grant side-footing wide soon after when goalkeeper Jak Alnwick spilled Taylor’s long-range drive.
They were level on eighteen minutes. Tariqe Fosu’s perseverance won a corner, with defender Naby Sarr heading the set-piece back across goal for the pink-haired Taylor to nod home.
Scorer turned provider four minutes later as Taylor wriggled his way into the area and squared for Joe Aribo to poke home his first goal of the season.
The Addicks only held the lead for eight minutes though, as Borthwick-Jackson rifled home from range after a half-cleared corner came his way – earning his first Scunny goal in the process.
Grant was guilty of poor decision-making moments after when slipped through on goal. He elected to shoot at goal, despite teammate Aribo being wide-open for a tap-in to his left. Alnwick smothered the striker’s effort and the game was flipped on its head again within seconds.
Taylor’s loose ball in the Charlton half was picked off by Borthwick-Jackson, who played a neat one-two with Humphrys before claiming his second of the game.
Humphrys fired straight at Steer early on in the second-period, before Bowyer threw Ben Reeves into the action – Darren Pratley making way.
Reeves was involved immediately as his corner fell to Josh Cullen, who saw his shot charged down, with Fosu firing over shortly after.
Borthwick-Jackson then drove a loose-ball at goal but Steer was equal to it, with Grant’s dangerous low-cross having just too much on it for Taylor at the other end soon after.
Fosu was an inch away from levelling the scores with just over a quarter of the game left. His arrowed drive from inside the area smacked the inside of the far-upright and came out.
The visitors were level with 21 minutes left to play. The Addicks worked a free-kick into the feet of Taylor, who laid the ball off for Aribo to touch home his second of the contest.
The rollercoaster ride wasn’t finished there. Jason Pearce was adjudged to have handled the ball inside the area, with referee Darren Drysdale pointing to the spot after some hesitation. Morris, who scored twice in this fixture last season, fired it high down the middle to regain the lead for Stuart McCall’s side.
Igor Vetokele came on for Fosu as Bowyer used his last throw of the dice with nine minutes left – before the Addicks benched was left fuming as Dijksteel was denied a penalty after appearing to be felled in the area.
And the game was killed off three minutes into added time as Humphrys touched home at the far-post, with Charlton short at the back as they went in search of an equaliser.