Preview - Allegri downplays Juventus' favourites tag before Porto bout

By Ed Dove

LISBON (Reuters) - Juventus' rampant domestic form doesn't make them Champions League favourites, according to coach Massimiliano Allegri, but the Serie A leaders are looking increasingly unstoppable before they meet FC Porto in the first leg of their round of 16 on Wednesday.

Juve's 4-1 victory over Palermo on Friday extended their winning streak in the league to six matches and, seven points clear, they remain on course for a record sixth straight Scudetto.

Since shifting to a 4-2-3-1 formation after a defeat at Fiorentina in mid-January, Juventus are also playing with the kind of fluid ferocity that many of their continental rivals lack.

They now turn their attentions to the Champions League, where a date with Porto offers a stern examination of claims that their domestic form makes them favourites for Europe's grandest prize.

"The thing that makes me smile is that when I arrived here three years ago there was a fear we wouldn't even beat Malmo (in September 2014)," Allegri told journalists. "Now we've gone the opposite way, with people saying Juventus are the number one favourites for the Champions League.

"You need to be balanced in these things. What we have to do is to beat Porto on the pitch," he said. "Porto knocked Roma out in the playoffs, are used to playing these kinds of games and that counts in the Champions League.

"Playing (at Porto's Estadio do Dragao) is absolutely not easy," he continued. "We need to go there with extreme caution, knowing that to go through we have to work hard and suffer."

Squad rotation has underpinned Juventus' Serie A consistency and Allegri will have to shuffle his pack again for Porto. Giorgio Chiellini and Andrea Barzagli are both doubtful with muscle problems and playmaker Miralem Pjanic is struggling with an inflamed left ankle.

Porto, second in the Portuguese top flight on 53 points after beating Tondela 4-0 on Friday, have no injury concerns or suspensions, although Andre Silva and Felipe are one booking away from suspension.

"We feel like we're on the level of the others and we have to play to win," concluded Allegri, who guided Juventus to their last Champions League final, in 2015.

"We can't go from being full of depression before Malmo -- trust me, I remember it -- to being euphoric now."

(Editing by Larry King)