Sarri reflected on a missed chance.
"It's a shame, because if you no longer have the strength to get up and defend inside the penalty area, against the players Roma have, the chances of paying a high price are significant. And unfortunately we paid it," Sarri said.
"We had a difficult first half, we did very well for the first 30 minutes of the second half, with the chance to go 2-0 up. And then probably, running out of fuel, we just couldn't keep doing what we'd done in that first half hour of the second half.
"We paid for it. There's real regret about how the result unfolded against the team that's in the best form in Serie A right now, and could be one of the title contenders, but there are also positive signs."
The Atalanta coach was clear lessons had to be learned quickly.
"It's clear that from here we have to start again. We have to be very humble, which is the characteristic that has made Atalanta strong in recent years," he said. "Humility that we need to maintain, knowing there will be suffering but also plenty of desire to grow."
AS Roma boss Gian Piero Gasperini, speaking to DAZN, praised his players for the comeback against his old club.
"We've been building certain qualities for some time, I'll never stop praising these lads. Losing today and having to talk about it would have been difficult, just look at the numbers," Gasperini said.
"When we scored we went with momentum, even though it was very close. The game had got complicated, our first-half dominance hadn't translated into goals, then Ederson hit a great shot and Atalanta's strong players were causing us problems in transition. Once we made changes at the back we didn't suffer any more, and up front Soulé and Castro gave us a great boost."
Asked about the fresh legs, Gasperini explained.
"In the first half we had lots of half-chances and weren't very good at combining up front with the three forwards. We were sloppy in the final touch and the quality of the shooting, probably also the heat and some fatigue — the players aren't machines," he said. "The introduction of Castro and Soulé, who were fresh, brought us advantages."
Gasperini praised his side's composure after going behind.
"A lot, this was the most important aspect of the comeback. We never threw away our shape or the way we kept the pitch open and made our runs, playing with clarity through our teammates' movements. On occasion Carnesecchi was extraordinary."