An early own goal from Timo Hübers handed Union Berlin a 1-0 victory at Cologne Sunday and took the capital club top of the Bundesliga for the first time in their history.
Fans of the Köpenick cult club revelled in their latest success of a strong start to the season which has brought four wins and two draws for a provisional best 14 points.
Freiburg could have reclaimed top spot when they hosted Borussia Mönchengladbach in the final game of the weekend but were held to a frustrating 0-0 draw.
Champions Bayern Munich are two points short of Union after three successive draws and one behind second-placed Freiburg.
A frantic start brought Union the early opener when Hübers turned in Sheraldo Becker's cross and Jordan Siebatcheu had a penalty saved by Marvin Schwäbe after handball from the hosts' Luca Kilian.
Becker had a goal disallowed for offside to cap a crazy first 15 minutes while after the break Union's Christopher Trimmel hit the bar bar from a well-worked free-kick before Killian's second yellow card for denying a counter-attack ended Cologne's faint hopes of an equalizer.
"We are on a run," Union captain Trimmel told DAZN. His team "did well in phases, but we have to improve when it comes to playing with the ball".
Cologne attacker Florian Kainz was annoyed: "In the first half it was far too little."
Both clubs are between mid-week European fixtures and made five changes to their starting eleven with the rotation handled much better by Union, who even recalled Timo Baumgartl to the bench for the first time since his testicular cancer diagnosis in April.
"It was a deserved win," admitted Cologne coach Steffen Baumgart. "It's been a while since I've seen a team here play as well as they did in the first half an hour."
Union had an anxious wait for Gladbach to help them out in Freiburg, which they did largely thanks to inspired goalkeeper Yann Sommer.
The Swiss keeper made saves from Michael Gregoritsch, Ritsu Doan and Jeong Woo Yeong though at the other end Marcus Thuram also tested Mark Flekken.
"It was a good 0-0 today," said Gregoritsch. "It was a good performance, we won the ball well a lot.
"We played a good game and 0-0 is okay because Gladbach also did well and had chances."
Gladbach edged up to eighth with their draw, behind local rivals Cologne on goal difference.
"It was a top game, to and fro," said Gladbach midfielder Julian Weigl. "I think can take the point with us [happily]."