Inter missed the chance to move within three points of Serie A leaders Juventus as they slipped to a shock 4-1 defeat at Atalanta.
The Nerazzurri held Barcelona to a 1-1 draw in the Champions League in midweek and their exertions in that game appeared to have an adverse effect on their performance in Bergamo.
Luciano Spalletti's side, who had won seven straight league fixtures, were on the backfoot from the off and were fortunate to only be 1-0 down at the interval as Atalanta spurned a host of chances following Hans Hateboer's eighth-minute opener.
A controversial penalty helped Inter punish Atalanta's profligacy and level through Mauro Icardi shortly after the restart but Gianluca Mancini, having conceded that spot-kick, thumped in the hosts' second before Berat Djimsiti and Alejandro Gomez made the game safe. Atalanta go seventh and Inter, who had Marcelo Brozovic sent off late on, will be nine points behind Juve if they beat AC Milan.
The theme for the first half was established in the opening four minutes as Duvan Zapata's curling effort forced a diving save from Samir Handanovic, who then produced an even better one to keep out Hateboer's follow-up.
Four minutes later, though, Hateboer did open the scoring, sliding in at the far post to turn home Robin Gosens' inviting ball.
Danilo D'Ambrosio deflected against his own post in another Inter escape, Josip Ilicic then somehow scuffing a Zapata delivery wide from point-blank range with the goal at his mercy.
Zapata himself saw numerous chances go begging late in the first half, Handanovic produced two further excellent saves from Ilicic and Rafael Toloi and Mancini glanced a header narrowly wide of the post from a corner as Inter inexplicably managed to survive until half-time with parity still within grasp.
And just two minutes into the second half parity was restored in very contentious fashion. Mancini was harshly judged to have handled in the area and Icardi coolly stepped up to slot his spot-kick into the bottom-right corner.
However, Mancini enjoyed redemption two minutes after the hour when he powered home Ilicic's left-wing free-kick with a superb header before Djimsiti's near-identical goal and a stunning long-range effort from Gomez, sandwiched by Brozovic's second yellow for a rash foul on Ilicic, made the points safe.
What does it mean? Inter fall flat after Barca point
Inter were full value for their point against Barcelona, earned by a late Icardi equaliser. But after seven straight league wins, the Nerazzurri's form faltered in Bergamo.
Mancini makes amends
Fabio Maresca's decision to award a penalty to Inter was a poor one. Mancini had no time to move his hand out of the way but, rather than crumble, Atalanta rallied and Mancini was a fitting hero. Performances akin to this one will fuel hope of a return to Europa League football for Gian Piero Gasperini's side after reaching the round of 32 last season.
Inter midfield goes missing
A midfield with talent such as Brozovic, whose difficult outing was made more miserable by his late red, and Matias Vecino should be able to have a measure of control in most games but Inter's engine room was completely overrun in the first half, allowing Atalanta a period of dominance they should have made more of.
Key Opta Facts:
- Mauro Icardi has found the net in five Serie A appearances in a row for the very first time in the competition (seven goals).
- Hateboer's goal has interrupted a 296 minutes streak in which Inter had kept the clean sheet in the Italian top-flight.
- Atalanta have found one goal with 16 shots attempted in the first half whilst they have scored three goals with the only three shots fired in the second half.
- Atalanta have now scored nine Serie A goals from defenders, at least four more than any other team this season.
- Danilo D'Ambrosio played his 150th game with Inter in all competitions.
What's next?
Spalletti will have some selection decisions to make as they welcome Frosinone just four days prior to a crucial Champions League clash with Tottenham. Atalanta visit struggling Empoli.
