Second-placed Inter Milan were held to a third successive 1-1 draw on Sunday in their Serie A match against Cagliari.
But their misery came from within somehow, after Radja Nainggolan, a player they loaned to Cagliari for this season, scored a second-half equaliser for the Sardinian side.
The fiercely competitive Belgian, who was told by Inter Milan coach Antonio Conte that there was no place for him this season, stunned the San Siro with a 78th minute goal.
It canceled out Lautaro Martinez’s first half opener for Inter Milan.
Martinez was sent off in stoppage time for his furious reaction after being given a yellow card for a foul.
He had to be ushered away by teammates as he continued to remonstrate with the referee.
The game ended in chaotic scenes as Inter Milan staff, including Conte, surrounded the referee to protest, with a livid Conte refusing to give any interviews.
Chinese-owned Inter Milan have 48 points from 21 games, three behind Juventus who were away to Napoli later on Sunday, and three more than third-placed Lazio who meet AS Roma.
“On the one hand, I’m sorry I scored. I have a lot of respect for Inter Milan, their fans and my team mates,” said Nainggolan.
“But, on the other hand, I’m happy. They treated me a little badly, as if I were a little player.”
Inter Milan’s players wore shirts with their names written in Chinese characters to celebrate the Chinese New Year.
With a midfield depleted by injuries and suspensions, Inter Milan gave Ashley Young his debut.
The former Manchester United player set up their goal in the 29th minute with a cross which Martinez met with a powerful header.
Cagliari protested that Martinez had pushed a defender and VAR officials finally confirmed the goal after a two-minute delay.
Alessio Cragno saved another Martinez effort with his feet but Inter Milan did not have it all their own way.
Goalkeeper Samir Handanovic had to palm away a looping header from Paolo Farago before half-time.
Stefano Sensi was also twice close for Inter Milan in the second half.
But they failed to add a second goal and paid the price when Joao Pedro pulled back the ball from near the corner and it ran on to Nainggolan.
His low drive from 25 metres took a deflection and went in off the foot of the post.
Romelu Lukaku was centimetres away from putting Inter Milan back in front, but their frustration boiled over in stoppage time with Martinez’s red card.
“We certainly didn’t draw because of the referee,” said Handanovic, the Inter Milan captain.
“We only complained because their forwards were given fouls and ours weren’t. We should have finished off the match, and then we wouldn’t be talking about all this.”