Champions League: Lionel Messi Nets Hat-Trick as Barcelona Hit Celtic For Seven

Lionel Messi bagged a hat-trick and Neymar grabbed four assists as Barcelona launched their Champions League campaign in style with a 7-0 thrashing of Celtic on Tuesday.

Messi and Neymar were reunited with Luis Suarez from the start for the first time this season and took no time in getting reacquainted as all three were on the scoresheet.

Two goals from Messi either side of Moussa Dembele's missed penalty for Celtic gave Barca a comfortable half-time lead.

And there was no let-up for the Scottish champions after the break as Neymar, Messi, Andres Iniesta and a Suarez double completed the rout.

"It has been many games since we have been able to enjoy being on the pitch together and today we did," Suarez told TV3.

Suarez was lauded as the best striker in the world by Celtic manager Brendan Rodgers, who was in charge of the Uruguayan for two years at Liverpool, on the eve of the game.

And Rodgers admitted the gulf in class told, but claimed there was no reason for Celtic to be embarrassed.

"There can be no embarassment because they do that to better teams than ourselves," said Rodgers.

"They are special players. It is a front three that can occupy as many players as you want.

"We had a back five, but their movement speed and touch combined, they are world class players and they showed that tonight."

However, Barca could face further sanctions from UEFA after thousands of separatist Catalan flags were again flown at the Camp Nou.

The Spanish champions were fined 150,000 euros (USD 170,000) by UEFA for the presence of the flags during last season's competition, 50,000 euros of which was suspended for two years.

Messi had started Saturday's shock 2-1 defeat to Alaves on the bench due to the after-effects of a minor groin injury, but took just three minutes to make his presence felt with a rising drive into the top corner from Neymar's lovely through ball.

However, Celtic had a great chance to level against the run of play when Dembele surged onto Scott Sinclair's pass and was upended by Marc-Andre ter Stegen.

Dembele was Celtic's hat-trick hero in a 5-1 thrashing of Glasgow rivals Rangers on Saturday, but he failed to add to his burgeoning reputation as Ter Stegen flew to his right to turn the Frenchman's penalty behind.

The German 'keeper has now saved three of the four penalties he has faced in the Champions League.

Barca immediately upped a gear and doubled their advantage three minutes later when a sensational exchange of passes between Neymar and Messi freed the latter to tap home his second of the night despite the presence of seven Celtic defenders in the area.

The one-way traffic continued after the break as Dorus de Vries could only parry Neymar's free-kick into the top corner for his first goal of the season.

Iniesta had been introduced at half-time and for all Messi's magic, the midfield schemer struck the goal of the night with a ferocious volley from Neymar's cross.

Suarez showed his unselfishness rather than his killer instinct a minute later by squaring for Messi to roll home and complete his sixth Champions League hat-trick.

Suarez did eventually get his goal, though, as he controlled another Neymar chipped pass before swiveling and smashing the ball into the roof of the net past a helpless de Vries.

And Messi's low cross was prodded home from close range by Suarez to cap a humbling evening for Rodgers's men on their return to the Champions League after a three-year absence.