Atalanta coach Gian Piero Gasperini admits they were caught out by Cagliari's passion in Sunday's defeat.
La Dea took the lead, but were beaten 2-1 by the Sardinians.
Gasperini said: We conceded a bad goal, as before that Cagliari had not really caused us any problems, but it gave them a second wind and we struggled.
We had the sensation that Cagliari had this fighting spirit. We had several scoring opportunities, but lacked quality upfront. Perhaps a draw would've been the fair result."
Gasperini took off substitute Mitchel Bakker just before Cagliari scored their winner.
He was struggling and couldn't even jump for the headers," he explained. "He cannot play like this, he was not in any condition to continue."