An own goal from debutant Paddy McNair saw David Moyes' first game in charge of Sunderland end in late heartbreak against Manchester City.
Sunderland fell behind four minutes in after Patrick van Aanholt's clumsy challenge on Raheem Sterling inside the area, Sergio Aguero scoring from the spot.
But the Black Cats didn't cave in and got their rewards 20 minutes from time, Jermain Defoe equalising with a smart finish to send the travelling supporters into raptures.
Their joy didn't last though, sub McNair nodding into his own goal at the death, with Sunderland losing 2-1.
Moyes started Lamine Kone despite a turbulent week as a result of him handing in a transfer request over claims he hadn't been offered a promised new deal.
Sunderland put the record straight on the eve of the City game after Moyes revealed that the club will honour a verbal promise made by the previous regime - on September 1.
It didn't seem to distract the Ivory Coast international though, with Kone his usual self alongside the impressive Younes Kaboul.
Two minutes in and Sunderland were awarded a free-kick 25-yards from goal, van Aanholt's deflected effort palmed away by Willy Caballero, in for the dropped Hart.
Two minutes later and the Dutch full-back was involved again but for all the wrong reasons.
Sterling got the better off him inside the area, with van Aanholt fouling him for a clear penalty. Aguero stepped up to blast the ball into the left-hand side of the net.
City looked rampant in the opening stages but twelve minutes in and Sunderland were inches away from equalising.
Caballero fluffed a clearance, Duncan Watmore pounced before playing in Lynden Gooch who played a superb ball across the face of goal. Fabio Borini just couldn't connect.
Vito Mannone saved comfortably from Aguero as City threatened to add to their early lead, while Manuel Nolito's ambitious effort 23 minutes in sailed just past the post.
City were dominating possession but doing little with it to threaten Mannone in the Sunderland goal.
Kone and Younes Kaboul impressing at the back, with Defoe looking sharp up front.
Just past the half hour mark, Defoe claimed for a penalty after being involved in a minor tussle with City's £47.5million man John Stones but referee Robert Madley wasn't interested.
Defoe almost levelled five minutes before half-time, Kone jumped highest to nod the ball into the ball of Defoe who fired an instinctive first-time shot at goal.
Caballero was alert and produced a fine stop.
Half-time: Manchester City 1 Sunderland 0
The start of the second half followed a similar pattern to the first, with City dominating possession but doing little to penetrate the Cats back-line.
Guardiola brought on Jesus Navas 58 minutes in, replacing Nolito who had given Sunderland debutant Love a tough time in the opening stages of the first half.
It was almost 2-0 an hour in.
Sterling sped past Love before firing a cross into the box, the ball eventually fell to Aguero but the Argentinian striker blasted his shot wide from close range.
A let off for Sunderland who turned to Adnan Januzaj for his debut after arriving on loan from Manchester United and Wahbi Khazri, with Watmore and Gooch departing.
The added impetus from the impact subs worked, with Defoe popping up with a fine equaliser 71 minutes in.
Borini laid the ball off to Rodwell, whose deft pass released Defoe inside the penalty area, the 33-year-old calmly stroking the ball past Caballero to make it 1-1.
Defoe hadn't been in the game much second half but popped up when it mattered.
Moyes looked to tighten up for the remaining seven minutes, with former Manchester United man Paddy McNair making his Sunderland debut from the bench.
Januzaj was pushed up front alone for the final stages.
Sunderland couldn't hold on though, Navas burst down the right-hand side and produced a wicked cross that wasn't dealt with.
McNair nodding the ball into his own net at the back post after 87 minutes. Sub Kelechi Iheanacho should have made it 3-1, his shot deflected over late on.
Heartbreak for Sunderland on the opening day.
Full-time: Manchester City 2 Sunderland 1
Manchester City (4-2-3-1): Caballero, Sagna, Stones, Kolarov, Clichy (Iheanacho, 81) Fernandinho, Silva (C), Nolito (Navas, 59), De Bruyne, Sterling, Aguero
Subs Not Used: Hart, Zabaleta, Fernando, Delph, Otamendi.
Booked: Koloraov (90)
Goals: Aguero (4, penalty), McNair (own goal, 87)
Sunderland AFC (4-1-4-1): Mannone, Love, van Aanholt, Kaboul, Kone, O’Shea (C), Rodwell, Gooch (Khazri, 64), Watmore (Januzaj, 64), Borini, Defoe (McNair, 83).
Subs Not Used: Pickford, Djilobodji, Lens, Asoro.
Booked: Gooch (42), Love (67)
Goals: Defoe (71)
Referee: Robert Madley (Wakefield)