Brighton inflicted a second straight Premier League defeat on Manchester City with a 1-0 win to close within two points of the leaders on Saturday.
Third-placed Brighton ended their wait for a first ever away win against City at the 18th attempt to bolster dreams of challenging for the title.
The Seagulls have never won a major trophy but have already beaten champions Arsenal convincingly this season to show their title credentials.
Fabian Hurzeler's men got revenge for defeat to City on penalties in the League Cup on Wednesday.
Hurzeler felt aggrieved at that result after his side twice led at the Etihad and this time held on after Yasin Ayari slotted them into an 11th-minute lead.
Bart Verbruggen was inspired in the Brighton goal to see off a City onslaught after half-time.
But the visitors were well worthy of a famous win and could also have added to their lead when Jack Hinshelwood hit the side-netting late on.
City won their opening seven league games as Enzo Maresca made a flawless start to the daunting task of succeeding Pep Guardiola.
However, the 10-time English champions know their results on the field may count for little this season unless they can successfully overturn a guilty verdict on over 100 charges of breaking Premier League financial rules.
City have appealed, but if that ruling is upheld they are likely to face a severe points penalty and possible relegation from the English top-flight.
Defeat for Maresca's men means Arsenal can go top of the table if they avoid losing at Liverpool on Sunday.
