New signing Scott Twine came off the bench to hit a dramatic late winner as Bristol City beat Millwall in a see-saw seven-goal Championship thriller at Ashton Gate.
The Robins had earlier appeared to be cruising thanks to two goals in the opening 12 minutes from Anis Mehmeti and Sinclair Armstrong.
But Millwall teenager Romain Esse's second goal in five days soon after the interval sparked a sensational turnaround as the Lions scored three times in 13 minutes.
Tom Bradshaw's penalty brought Millwall level before Duncan Watmore volleyed a sumptuous third to turn the match on its head – his third goal in Millwall's opening two Championship games.
However, the hosts were not done as Fally Mayulu steered Max Bird's cross into the bottom corner to equalise, before Twine – who sealed a permanent move from Burnley in midweek – won it two minutes from time.
It was very much a case of deja vu for the Lions - who have twice battled back from two-goal deficits in the opening two weekends of the season yet remain without a point.
They were undone by a stoppage-time Watford winner seven days earlier and while Twine's decisive strike came slightly earlier - in the 88th minute - it will have stung no less.
Summer signing Armstrong, who arrived for an undisclosed fee from Championship rivals Queens Park Rangers, was at the forefront of the hosts' quickfire start.
The Republic of Ireland striker, 21, surged down the right to provide the cross for Mehmeti’s third-minute opener.
Armstrong then opened his own Robins account nine minutes later, smartly stealing in between two Millwall defenders to bury a header from Bird’s inviting in-swinging centre.
Ryan Leonard hit the post for the visitors before the break but a superb goal from Esse, jinking in between two defenders before finding the bottom corner, gave them a lifeline.
George Tanner's handball allowed Bradshaw to level from the spot and when Watmore showed fantastic technique to volley home a loose ball in the box, the turnaround seemed complete.
However, there were two more twists in the tale as, first, Bird provided his second assist of the game, a low cross swept home by Mayulu.
Then Twine - who spent the second half of last season on loan at Ashton Gate before moving permanently this week - sent his new home into raptures by guiding home Joe Williams' cross with a cushioned volley.
Bristol City head coach Liam Manning told BBC Radio Bristol:
"It aged me quite a bit. What a rollercoaster. For a fan it's a terrifically enjoyable afternoon being ahead, going behind and then responding.
"We were at the end of a sucker-punch last week to concede so late, so to do that today and win at the end in the manner that we did I think was terrific.
"At the same point we have to take a huge amount of learning and what we can't do is be two up and in really good control of the game and throw it away - at this level you won't be able to do what we did every week.
"Delighted with the response of the lads, delighted with the togetherness, delighted with the quality of the goals, but we also have to take the lesson as well."
Millwall head coach Neil Harris told BBC Radio London:
"Poor goals have cost us. I praise Bristol City and their bench, that's made the difference.
"Look at the impact their bench is bringing to the game and look at the group that we're working with at the moment.
"I was hugely frustrated that for 75 minutes we were in front, albeit we went behind with a couple of really poor goals again, but we got ourselves back in front and we looked comfortable, we looked the best team.
"Then they bring on attacking players and they make an impact. That is the difference at any level of football but especially the first week of the season when you can bring on quality like that."