Juventus missed a chance to clinch a record-extending ninth straight Italian league title as it lost 2-1 at relegation-threatened Udinese on Thursday.
Ilija Nestorovski canceled out Matthijs de Ligts opener and Seko Fofana grabbed the winner in stoppage time to keep Juves celebrations on ice.
It was the latest twist in an extraordinary title race which has seen three of the four contenders repeatedly drop points. Inter have won only two of their last six matches and Lazio had taken one point from a possible 15 before Thursday.
"We lost a bit of order," said Juve coach Maurizio Sarri. "We lost in the 93rd minute because we were trying to win at any cost. This season is difficult, all the teams are playing in conditions different to the usual ones and everyone is tired."
Atalanta's next match is at AC Milan on Friday while Inter visit Genoa on Saturday and Juve host Sampdoria on Sunday.
Juventus had a lucky escape when Danilo headed Ken Sema's cross against the post while Udinese's Bram Nuytinck was also spared embarrassment when his back pass almost trickled into the net but goalkeeper Juan Musso pushed it wide just in time.
Musso also did well to turn away a Paulo Dybala shot and Cristiano Ronaldo was close from long range before Juve broke the deadlock three minutes before halftime.
A Udinese clearance landed at the feet of De Ligt and the Dutchman took one touch and drove a low shot into the net from 25 metres.
However, Udinese found a deserved equaliser seven minutes after the restart. Sema swung a cross over to the far post where Nestorovski met it with a diving header which flew into the net.
Udinese defended doggedly before snatching the winner on the break. Ivorian Fofana collected a loose ball on the halfway line, charged forward, nutmegged De Ligt and slotted his shot under Wojciech Szczesny to give his side a memorable win.(With inputs from Agencies)