Barcelona full-back Jordi Alba warned Celtic will be faced with the "best strikers in the world" but admitted they'll have to keep it tight at the back themselves.

Lionel Messi, Luis Suarez and Neymar could start together for the first time this season in Tuesday's Champions League Group C opener against the Scottish champions.

All three were involved at some stage in the Catalan outfit's shock 2-1 home defeat to Alaves on Saturday.

Messi has been struggling with a groin strain and will be assessed before the game. Neymar is only back after his Olympic exploits with Brazil and Suarez started on the bench at the weekend.

Barca's deadly striking triumvirate has scored 254 goals between them over the past couple of seasons but Alba says defence will just be as important as attack.

"They are the best strikers in the world... but if we play well defensively, we'll be more successful," he said.

"We need to have the ball, we need to be aggressive, to recover the ball, and to try and create opportunities."

Celtic's 5-1 victory over city rivals Rangers was the perfect preparation for the massive game at Camp Nou.

However, despite the impressive attacking performance there are some question marks over a defence which has conceded eight goals in their last five games.

Alba says it will be a difficult backline to breach.

"It will be tough to create opportunities against them, but that's what we are here for," he said.

"It's important to have a good start to the competition and get the three points."

Barcelona won their fifth Champions League title in 2014-15 which was part of an illustrious treble, and Alba says the club have their sights set on sweeping the board for honours again this season.

He said: "We are motivated for all competitions. We want to win every title, as many as we can. That's the way we are. We want to get people excited game after game."