Manchester City failed to win for the eighth time in nine games in a 2-2 draw at Crystal Palace on Saturday, while Brentford made it seven wins from eight games at the Gtech Community Stadium with a thrilling 4-2 victory over Newcastle.
City had the chance to go second in the Premier League but failed to build on a 3-0 win over Nottingham Forest in midweek, which had appeared to stop the rot for the English champions.
Pep Guardiola's men got off to the worst possible start at Selhurst Park when Daniel Munoz raced on to Will Hughes' pass to fire Palace in front after four minutes.
Erling Haaland's towering header from Matheus Nunes' cross brought City back level and took the Norwegian level with Liverpool's Mohamed Salah on 13 Premier League goals in the battle for the Golden Boot.
The visitors started the second half strongly but were hit with a sucker punch when Maxence Lacroix powered home Hughes' corner. Rico Lewis found the top corner to level once more for City, but was then sent off six minutes from time.
Fourth-placed City close to within eight points of leaders Liverpool, but more dropped points is another blow to their chances of making it five consecutive titles.
The final league derby between Everton and Liverpool at Goodison Park will have to be rescheduled after Storm Darragh battered western regions of England with high winds and heavy rain.