Reading's unbeaten 15-match home run came to an end when they lost 1-0 to Bristol City in a hard-fought Sky Bet Championship contest at the Madejski.
Although Reading dominated much of the game, they could not get past agile City goalkeeper Frank Fielding, who made several good saves.
City showed in attack only in patches but clinched victory in the 84th minute when centre back Aden Flint drove in from 10 yards out. Reading, undefeated at home in all competitions since losing 1-0 to QPR in the league in January, had signed off for the international break with a 2-0 win at Birmingham.
Sone Aluko, the forward signed for a club record £7.5m from Fulham last month, made his debut for Jaap Stam's side. City had only one victory in their opening five Championship matches but had drawn three in a row before making the short trip up the M4 to Berkshire. Yet they began promisingly, with Famara Diedhiou having a chance from a 25-yard free-kick - only to send it too high.
Reading replied with an excellent deep cross from Modou Barrow, which flew over Fielding, but there was no one on hand to touch it in at the far post. Bobby Reid volleyed over from a Callum O'Dowda cross as City pushed forward again, but Reading were quick to up the tempo.
Aluko, who had become increasingly influential, shot from distance but off target, then supplied a fine cross that Barrow sliced well wide. Reading kept up the pressure and Liam Kelly struck a low 25-yard shot that forced an acrobatic save from Fielding. Kelly was swiftly involved again but, after collecting an Aluko pass, shot tamely into the side-netting.
City defender Nathan Baker was perhaps fortunate to escape a red card when he brought down Barrow, who was galloping clear, but referee James Linington deemed it worthy only of yellow.
Reading started the brighter after the interval and, with thunder and lightning crackling overhead, Jon Dadi Bodvarsson somehow miscued a Barrow cross from six yards out.
Leandro Bacuna's 20-yard effort was well saved by Fielding before City were afforded some respite when Reid broke away to set up Jamie Paterson, who flashed a shot wide. Bodvarsson astonishly again miscued with the goal gaping, this time from an Aluko cross, and City snatched the winner six minutes from time.
Reading had several chances to clear the ball but failed to do so, allowing Flint to pounce with a clean strike. Home keeper Vito Mannone got a hand to it but could not prevent it from trickling over the line.
Jaap Stam: "We had plenty of opportunities to score and that's what it's all about. It's a cliche but if you don't finish them off yourself, the opposition eventually scores and that's it.
"We knew what City are like - they're a good side - and they didn't want to let us play and get into our comfort zone. That's what they did at times and they did it well. We needed to score but didn't. It was harsh that we lost, especially as it was at home."
Lee Johnson: "You want your best available squad to work with and obviously Aden is an established Championship player. I've had a very honest and open relationship with him leading up to the closing of the transfer window and, to be fair to him, he's never thrown his toys out of the pram.
"He signed a new four-year contract six months ago and it's got three-and-a-half years to run. He's come in every day, he's trained properly and that's what you need to do to be successful. I was really pleased with the performance today. It was great to have an international break before so that we could really prepare for this game."