Inter Milan handed AC Milan a way back into the Serie A title race as a late Atalanta goal held them to a 1-1 draw and second game without a win.
Pio Esposito fired them in front at San Siro with a low 26th-minute strike that squirmed under the arm of Atalanta goalkeeper Marco Carnesecchi.
The visitors were angry the goal was allowed to stand, claiming Inter full-back Denzel Dumfries had committed a foul in the build-up.
But the Dutchman himself was then left infuriated when Nikola Krstovic scored an 82nd-minute equaliser.
Dumfries went down under pressure from Atalanta substitute Kamaldeen Sulemana, whose shot was parried by keeper Yann Sommer into the path of Krstovic to finish.
The video assistant referee (VAR) did not disallow the goal, much to the home side’s dismay, and Inter boss Cristian Chivu was sent off for his protests.
Inter were further incensed moments later when the VAR denied what they felt was a clear penalty for a Giorgio Scalvini challenge on Davide Frattesi.
After being eliminated in the Champions League play-off round by Bodo/Glimt, Chivu’s side have endured a difficult month, failing to score in back-to-back games and having their 15-game unbeaten league run ended by city rivals AC Milan last weekend.
Inter had 16 shots – 11 inside the penalty area – but were wasteful in the absence of injured top scorer Lautaro Martinez.
Marcus Thuram, Federico Dimarco and Dumfries spurned presentable opportunities as their side racked an xG rating of 1.59.
Inter are eight points clear at the top of the table, but AC Milan could cut the lead to five, with nine games remaining, if they win at Lazio on Sunday (19:45 GMT).
A 15th consecutive Serie A match against Inter without victory has left Atalanta seventh in the table, four points off Como in fourth place.