Juve dropped points for the first time this season on Saturday, drawing 0-0 with Fiorentina at the Stadio Artemio Franchi.
The visitors lost Douglas Costa and Miralem Pjanic to suspected hamstring and thigh injuries respectively before half-time and never really got going, with full debutant Franck Ribery the biggest threat for the home side.
Although Sarri, who watched on from the sideline for the first time this season after overcoming a bout of pneumonia, pointed out injuries and a general lack of fitness had an impact on Juve's display, he accepts his side were not up to scratch.
"We didn't put in a good quality performance," Sarri told Sky Italia. "It was a very complicated situation, as Fiorentina played well and we used up all our substitutions with injuries and had no more fresh legs to introduce.
"With all those variables, we did well in terms of character to get a point out of it. We lost possession too many times, which may also be a consequence of physical issues.
"Playing in mid-afternoon in Florence when it's realistically still summer is tough for everyone.
"We had difficulty on a purely technical level and I am confident a team with less personality would've lost. That is the positive and certainly a valuable quality to have a team that can fight it out for a point even when not in great shape.
"We had five players at the Copa America and eight on the treatment table, so we have half the squad at a more advanced fitness level than the rest.
"It was a difficult situation to deal with and we needed some time to get them all to acceptable levels, but the good news is that we tend to finish games strong."
Cristiano Ronaldo, Gonzalo Higuain and Douglas Costa started up front for Juve, and Sarri suggested the trio needed to do more to get themselves into the game, as well as assist defensively.
"When the team defends deeper, we need the forwards to come back and help more," added the former Chelsea boss.
"It was evident after 30 minutes that this was going to be extremely difficult."