In a fiercely competitive Champions League round on Wednesday, the 100-per-cent winning records of Pep Guardiola and Carlo Ancelotti with their new clubs finally came to an end.
Guardiola's Manchester City trailed three times at Celtic, levelled each time and finished strongly before having to settle for a 3-3 draw. The coach's winning streak to start the season ended at 10 matches.
Ancelotti, a three-time Champions League winner as a coach, had won his first eight games at Bayern Munich, but his team failed to impress in losing 1-0 at Atletico Madrid. It was a repeat of the result at the Vicente Calderon stadium when the teams met in the semifinals last season.
Barcelona played its part on a night of come-from-behind wins, 28 goals in eight matches and three missed penalties.
The five-time champion, missing the injured Lionel Messi, trailed at Borussia Moenchengladbach before scoring twice in a nine-minute period midway through the second half to secure a 2-1 win.
In Group A action, Arsenal and Paris Saint-Germain, who drew 1-1 in France two weeks ago, both won to take control in the standings.
Arsenal was at its slick-passing best in beating Basel 2-0 and threatened a rout after Theo Walcott scored twice in the first 26 minutes.
Arsenal and PSG have four points, and Basel and Ludogorets each has one.
In Group B action, Napoli extended its impressive home form, and its lead in the group standings, by beating Benfica 4-2.
The Italians raced to a four-goal lead in under an hour, with Marek Hamsik breaking the deadlock, Dries Mertens scoring twice and prolific Poland forward Arkadiusz Milik converting a penalty.
Benfica, which gave up a late leveller to Besiktas two weeks ago, scored twice late on through Goncalo Guedes and Salvio.
Besiktas got its second straight 1-1 draw after 18-year-old substitute Viktor Tsygankov earned Dynamo Kyiv a point in the 65th minute in Istanbul.
Napoli already has a four-point lead over Besiktas. Benfica and Dynamo each has a point.
In Group C action, a pulsating Scotland vs. England clash ended up 3-3 as Celtic gave Man City its biggest scare of the flourishing Guardiola era.
Moussa Dembele missed a penalty in Celtic's 7-0 drubbing in Barcelona but took only three minutes to banish that memory and score on Wednesday. That lead lasted only nine minutes until Fernandinho equalized.
Barcelona ended Borussia Moenchengladbach's long winning run at home with a 2-1 win. Barcelona, which is seeking its fifth Champions League title in 11 seasons, leads the standings by two points from Man City before the teams meet in Spain on Oct. 19.
In Group D action, Atletico Madrid and Bayern Munich were quickly reunited in the group stage after meeting in last season's semi-finals. Then, Atletico advanced on away goals after winning the first leg at home 1-0.
Atletico has six points, three clear of Bayern and with an early advantage in any head-to-head tiebreaker in the group.