Cristiano Ronaldo continues to be troubled by knee pain, with Juventus head coach Maurizio Sarri to discuss the injury with his star forward.

Ronaldo returned to the Juve side for Tuesday's 1-0 Champions League win at home to Atletico Madrid after missing a weekend victory away to Atalanta in Serie A.

The Portugal international appeared to struggle at times as Paulo Dybala's stunning free-kick ensured the Bianconeri will finish top of Group D with a game to spare.

Ronaldo was substituted in each of Juve's two league games prior to the international break, and Sarri accepts the 34-year-old's fitness must be managed.

"I haven't spoken to him yet about the pain in his knee," Sarri told Sky Sport Italia after Ronaldo completed the full 90 minutes. 

"But he looked to be in good shape, as in the final stages he was tracking back, fighting hard and helping out in defence.

"Dybala is world class, in a very positive period of form, so right now he is making the difference."

Though Juve maintained their momentum with another victory, Sarri was left frustrated with aspects of their performance against Atletico.

"We used up a lot of energy this evening, as is inevitable in the Champions League," he added. 

"I think we did very well but, like the Atalanta match at the weekend, we had to fight very hard to achieve the victory.

"It was above all a great first half, and we built on that. We tend to struggle more in Serie A to pass it around quickly.

"Perhaps there is more motivation for us in the Champions League, but that is a mistake, because we have to play this style of football in every tournament.

"I was angry in the second half, as we gave the ball away cheaply. The sensation was that, just like Atalanta, we allowed them to cross too much.

"Maybe we need to improve the intensity with which we close down these crosses and passes in wide areas."