Juventus will be without Leonardo Bonucci for Wednesday's Champions League last-16 match at Porto.

Centre-back Bonucci sustained a minor muscular problem during training and joins Juan Cuadrado (hamstring) and Paulo Dybala (knee) on the sidelines.

However, Juve head coach Andrea Pirlo is boosted by the return of Aaron Ramsey from a muscular complaint of his own - the Wales midfielder having been absent from the Serie A champions' four games so far across all competitions this month.

"Leo is not available, he had a little problem in training. We will evaluate but he is not available for tomorrow," Pirlo explained at his pre-match news conference.

"Ramsey can play while Dybala is not ready yet, but everyone wants to be with the team."

Porto followed their opening 3-1 defeat to Group C winners Manchester City with five consecutive clean sheets in this season's competition.

Pirlo knows Sergio Conceicao's men will prove a tough nut to crack and likened them to Diego Simeone's famously robust Atletico Madrid.

"I expect a very complicated match, they defend very well," he said.

"They are a team with a bit of the Atletico Madrid style: tight, compact lines.

"We must not force plays. The Champions League is a particular competition, different from the [Italian] championship.

"There are many teams fighting to win, everyone wants to do it and it depends a lot on [your form] when you face the teams. It is important to be mentally ready."

A 1-0 weekend defeat at Napoli due to Lorenzo Insigne's first-half penalty left Juve fourth in Serie A - eight points shy of leaders Inter, albeit with a game in hand.

It means the Bianconeri could relinquish possession of the Scudetto for the first time in a decade, but Pirlo insists his maiden season at the helm remains broadly on track.

"We won the Supercoppa Italiana, we are in the final of the Coppa Italia, we are in the running for the Champions League," he said.

"We are still well placed in the league. We are in the running on all goals and this is the most important thing."

Ending Juve's 25-year wait for a third success in Europe's premier competition would certainly represent a job well done. 

"The Champions League is a goal," Pirlo added. "The important thing is to believe in it, to know that we are a team that can reach the end. 

"This is the most important thing."