Barcelona coach Ernesto Valverde warned against snap judgements on his side and Juventus' Champions League aspirations despite losing key players in the transfer market.

The sides meet in their competition opener on Tuesday (1845 GMT) in a rematch of a quarter-final clash won 3-0 on aggregate by Juventus last season.

Barca are still coming to terms with the loss of Neymar to Paris Saint-Germain for a world record 222 million-euro fee ($267 million).

But Juventus have also seen the team that reached last season's Champions League final weakened by PSG snapping up Dani Alves and Leonardo Bonucci's move to AC Milan.

"They have lost Bonucci but they remain a very strong, good team," said Valverde on Monday.

"I can see the comments of comparing squads to previous seasons are the same in every country.

"People look at transfers and decide if a squad is stronger or weaker, but the time to do that is at the end of the season."

Juventus are also without the injured Giorgio Chiellini and Mario Mandzukic, but like Barca, have won all three of their league games this season to sit top of Serie A.

"In football every season is different from the last," said Juventus coach Massimiliano Allegri.

"The players change because that's how things go, but what counts are the results.

"Right now Juve can't do more than nine points in the league and Barca have done the same."

Despite the distraction of a chaotic summer off the field and ongoing calls for club president Josep Maria Bartomeu to step down, Barca have started La Liga in fine form.

Lionel Messi scored a hat-trick, while Ousmane Dembele set up a goal for Luis Suarez on his debut as Valverde's men thrashed local rivals Espanyol 5-0 on Saturday.

"It is always better to face this calibre of game after some victories with good sensations," added Valverde.

"Everyone wants to advance and have a chance of winning the Champions League.

"We are in very good form, we won 5-0, but that doesn't guarantee anything because our opponent has also started very strongly in the league."

Valverde could hand a full debut to Dembele after the 105 million-euro Frenchman only came off the bench for the final 20 minutes against Espanyol.

"He is training well, every day he is more integrated," said Valverde.

"He could start at any time, if it is not now then it will be shortly."

- Dybala threat -

Paulo Dybala was Barca's nemesis last season as his two goals in the Italians' quarter-final win drew comparisons with his international teammate Messi.

"What I did last year no one expected and now everyone expects that I can do it again," said Dybala.

"It isn't easy because playing against a team like Barcelona in a stadium like this is very difficult."

Dybala was one of many names linked with Barca as Neymar's replacement before they splashed out on Dembele.

However, having signed a new deal to 2022 and been handed the number 10 shirt at Juventus, even the chance to play regularly alongside Messi couldn't drag Dybala away from Turin.

"Luckily I have the chance to play with Messi in the national team.

"It is a privilege to have him as a teammate and for sure I can learn a lot from him.

"What might happen in the future I don't know, but I am very happy at Juventus."

Allegri lauded Dybala as along with Neymar "the two best young players in the world".

Yet, having lost in the final in two of the last three seasons to Barca and Real Madrid, Allegri insisted the Spanish giants remain favourites to win the competition again.

"Neymar is gone and he is a great player...but Barca along with Real Madrid are still the strongest team in the world."

Source: AFP