Massimiliano Allegri pinpointed fitness as the reason behind Paulo Dybala's waning form following a largely anonymous display against Frosinone.
Federico Bernardeschi came off the bench to add a second in stoppage time and issue Allegri a reminder of the attacking options at his disposal.
"He needs to play. I've always said Paulo's best physical attribute is his running," Allegri told Sky Sport Italia.
"He did some good things today. But he has to play. His technique and dribbling is useful and it will get better with fitness.
"Dybala has no need to feel this performance anxiety. You can be the best player in the world, but if you're not at 100 per cent mentally, the others will get to the ball faster.
"Mario Mandzukic is always first to the ball, but today he was a little less sharp because of fatigue, it's natural.
"We were expecting a difficult game and that's what we got. As the time advanced it got harder and harder to score a goal but we finally did thanks to Cristiano Ronaldo."
Frosinone managed to frustrate the champions until Ronaldo finally made the breakthrough in the 81st minute.
Defeat leaves Moreno Longo's men above only Chievo - who have had a points deduction - and without a goal to their credit this term.
"It's a shame. We did well for almost the entire match and a few minutes from the end I thought we could get a draw," Longo said.
"On paper this could have been lost from the beginning, but that was not the case."