Tom Lawrence's stoppage-time header gave Derby boss Frank Lampard a first managerial win in a 2-1 victory over Reading in the Championship curtain-raiser.
The Royals had the bit between their teeth from the outset and caused problems, nullifying the lacklustre Rams attack and troubling their opponents with continuous menacing forays into the final third.
Jon Dadi Bodvarsson gave the hosts a deserved lead when he headed home Mo Barrow's floated cross (52), but within 10 minutes, Chelsea loanee Mason Mount's drive escaped the grip of Vito Mannone, allowing the visitors to level proceedings (60).
Reading: Mannone (6), Yiadom (7), McShane (7), Ilori (6), Richards (6), Meyler (6), Kelly (6), Aluko (6), Swift (6), Barrow (8), Bodvarsson (7).
Subs: Baldock (5), Meite (n/a), Bacuna (n/a)
Derby: Carson (6), Wisdom (6), Keogh (6), Davies (6), Lowe (6), Bryson (6), Ledley (6), Mount (7), Wilson (6), Nugent (5), Lawrence (8).
Subs: Johnson (5), Bennett (6), Pearce (n/a)
Man of the match: Mo Barrow
The game looked to be heading for a 1-1 draw, but in the dying seconds, Lawrence completed the comeback when he met Mason Bennett's cross and planted a header beyond the former Arsenal stopper.
Heading into the new campaign after escaping relegation on the last season's final day and without a pre-season victory, the signs appeared bleak for Paul Clement's Royals heading into the season opener.
Despite having significantly less possession, the Royals were, however, resolute in defence; pacey and positive when coming forward.
Derby skipper Richard Keogh often suffered the ignominy of conceding after making poor passes out from defence last season and was almost left red-faced on two occasions in the first half in Berkshire; two lackadaisical passes allowed Bodvarsson the chance to carve out a pair of efforts, the Iceland striker's lack of comfort on the ball redeemed the Irishman.
Reading boss Paul Clement handed debuts to summer signings Andy Yiadom and David Meyler, with John O’Shea, Sam Walker, Marc McNulty and Sam Baldock taking their places on the bench. Liam Moore, meanwhile, misses out after handing in a transfer request.
Frank Lampard selected two debutants of his own in the shape of Mason Mount and Harry Wilson, but he was left without the injured Tom Huddlestone for the season opener.
Seven minutes into the second half, he finally made a chance count when he evaded the challenge of a host of Rams defenders to nod home Barrow's cross, but the elation was short-lived when Mount struck on the hour, largely thanks to Mannone's error.
The game swayed in both directions in the final half hour of the game and though Reading maintained their intensity, it was the visitors who completed the unprecedented turnaround when Lawrence leapt to meet Bennett's delightful cross to secure the win and spark jubilant celebrations in a relieved dugout.
Paul Clement: "I thought the scoreline was a little bit harsh. There were lots of things from my team that I was really pleased with and particularly the first-half performance. Start of the second half we scored a wonderful goal, well-worked down the left side, lovely cross and a beautiful header from Bodvarsson.
"Clearly they changed some things at half-time, went a bit more direct and opened the spaces up a bit. They got back into it with a good goal but the disappointing thing is if you are not going to win the game then don't lose it, particularly in the 94th minute. Fatigue played a part, but they produced that little bit of magic right at the death. It's a big lesson for us in the first game of the season and there are lots of games to play."
Frank Lampard: "But when you go one down, when you are trying to change your own game it is difficult. We got back with a slice of luck with the first goal but sometimes you make your own luck and obviously I feel sorry for Paul Clement and Reading because they probably didn't deserve to lose that game for sure.
"This is why I came into it. I had a long career as a footballer and I was very fortunate to have that. I've had a nice break but you miss the competitive nature. You miss the bug that is football, the mad things that it can do to you, mad things for me there at the end. I have to say i enjoyed it because it was a great result."
Man of the match - Mo Barrow
Despite being on the losing side, Barrow was a bright spark for Clement's men and a key part of their success for large swathes of the game. Barrow's electric pace caused problems and often created chances, including the floated cross that produced Jon Dadi Bodvarsson's opener. The Royals look deadly on the counter-attack and, should he remain in the same vein of form, the winger could prove to be an important asset this campaign.
Paul Clement's Reading travel to Nottingham Forest on Saturday, August 11, while Derby host Leeds in the day's late kick-off, a match you can watch live on Sky Sports Football from 5.30pm.