Lautaro Martinez gave Inter a fourth-minute lead against Atalanta at San Siro but the visitors were more than good value for their point.
Samir Handanovic's late penalty save rescued a point for Inter as the Serie A leaders laboured to a 1-1 draw against Atalanta at San Siro.
Lautaro Martinez combined wonderfully with strike partner Romelu Lukaku to score his 15th goal of the season in the fourth minute but Antonio Conte's side were then largely outplayed by a typically ambitious Atalanta.
Martinez was fortunate not to concede a spot-kick when he impeded Rafael Toloi towards the end of the first half, while substitute Ruslan Malinovskiy rattled the upright after the restart.
Robin Gosens poached a deserved equaliser 15 minutes from time and only Handanovic's heroics from Luis Muriel's 88th-minute effort from the spot denied Atalanta the victory.
Champions Juventus will go two points ahead of Inter at the summit if they win at Roma on Sunday.
The Nerazzurri's lethal front two made their presence felt early when Martinez took Lukaku's return pass away from Toloi and blasted under Atalanta goalkeeper Pierluigi Gollini.
In keeping with their vibrant attacking style, Atalanta sought a swift response – Mario Pasalic curling wide from the edge of the area before Duvan Zapata was unable to get enough power on his header to trouble Handanovic.
More textbook forward play from Lukaku and Martinez in the 22nd minute ended with Jose Luis Palomino heading the Argentina striker's chipped attempt off the line.
Martinez almost blotted a fine half when he grabbed at Toloi's ankle as the defender followed up a 41st-minute header saved by Handanovic, although referee Gianluca Rocchi inexplicably decided not to review the incident.
Atalanta boss Gian Piero Gasperini introduced Malinovskiy for Zapata in the 53rd minute and the Ukraine international almost had an instant impact, curling a sweetly struck left-footed effort from Alejandro Gomez's pass against the post from the edge of the area.
Waves of Atalanta attacks continued and they had their reward 15 minutes from time when Josip Ilicic's right-wing cross fell to Gosens for a smart back-post finish.
Alessandro Bastoni clumsily bundled into Malinovskiy during the dying minutes but fellow substitute Muriel fluffed his lines from 12 yards.
What does it mean? Inter give an inch
In a title race of fine margins, Juventus might just have stolen a march. Like the reigning champions, Inter have still only tasted defeat once in the top flight this season, although they are very fortunate that is still the case.
Atalanta are level on points with fourth-placed Roma and gave a further indication – on the day Lazio chalked up a club-record 10th consecutive league win – that Serie A's supporting cast might have plenty to say over the destination of the title.
Malinovskiy makes the difference
Atalanta were already more than holding their own when Malinovskiy entered the fray but his stunning strike against the upright seemed to kick Gasperini's men into a higher gear they never left for the remainder of the contest.
Working in tandem with the irrepressible Gomez, Malinovskiy posed persistent questions of Inter and should have been responsible for a winning goal.
Atalanta conundrum leaves Conte perplexed
Conte is not the first respected coach to be outplayed by this wonderful Atalanta side, who came into the clash on the back of consecutive 5-0 victories, but the way the game unfolded will hurt a shrewd and proud tactician.
For most of the second half, Inter were hanging on and looked nothing like champions in waiting. Conte delaying his first substitution until the 71st minute, when he introduced Borja Valero to an ailing midfield, gave the impression of a man baffled by the problems presented to him and unable to answer them.
Inter host Cagliari in the Coppa Italia on Tuesday, with Atalanta travelling to Fiorentina for their own round-of-16 clash on Wednesday.