Manchester City lost 2-1 to Basel for its first home defeat in 15 months but still advanced to the quarterfinals of the Champions League.
Qualification was a formality for the English club after its 4-0 win in Switzerland in the first leg and City coach Pep Guardiola fielded a virtual reserve team at Etihad Stadium.
City advanced 5-2 on aggregate.
Still, the loss - only City's fourth in all competitions this season - came as a surprise, particularly after Brazil striker Gabriel Jesus put the home side ahead in the eighth minute on his first start in 2018.
Mohamed Elyounoussi equalized in the 17th, and wing back Michael Lang earned Basel its latest victory over a Premier League giant by smashing a rising shot inside the near post through goalkeeper Claudio Bravo's attempted save in the 71st.
With qualification all but secured from the first leg, Guardiola played many of his fringe players and it showed at times. City's passing was often sloppy and Basel broke regularly through a home midfield featuring the 34-year-old Yaya Toure - the captain for the evening - and a player half his age, English prodigy Phil Foden.
It was from one of those breaks that Basel scored its equalizer, with Blas Riveros' cross deflecting off John Stones into the path of Elyounoussi, who drove home a shot from 10 meters.
That canceled out the opening strike by Jesus, who is facing a real fight to be City's first-choice striker for the remainder of the season with Sergio Aguero scoring 15 goals during the Brazilian's seven-week absence because of a knee injury.
Jesus worked hard but he was understandably rusty, the ball sometimes not sticking when it was played into him. He was in the right place at the right time for his goal, though, tapping in at the far post from Bernardo Silva's low cross.
Basel's winner came when Elyounoussi slipped the ball through for Lang to fire home from an acute angle.
It was City's first home loss since a 3-1 defeat to Chelsea in December 2016. Basel has also beaten United, Chelsea, Liverpool and Tottenham in European competition since 2011.