Barcelona’s lethal MSN — Lionel Messi, Luis Suarez and Neymar — dissected Celtic 7-0 while a deluge washed out Pep Guardiola’s eagerly awaited first Champions League game in charge of Manchester City.

There was no rain but there was a flood of goals at the Camp Nou, where a sparkling Messi hat-trick with four assists and a goal from Neymar, Andres Iniesta and a Suarez brace humiliated Celtic on Tuesday night.

"There can be no embarrassment because they do that to better teams than ourselves," said Celtic boss Brendan Rodgers.

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

Suarez, reunited with Messi and Neymar for the first time this season, told TV3: "It has been many games since we have been able to enjoy being on the pitch together and today we did."

Celtic will have to shrug off this worst ever European defeat as their next Group C outing is at home to City.

After the weekend derby defeat of Manchester United, City had Borussia Moenchengladbach firmly in their sights but the fixture was called off just 20 minutes before kick-off with the Etihad Stadium hit by heavy rain.

The match will now be played on Wednesday at 6.45 pm GMT.

Guardiola’s old side Bayern Munich, under new boss Carlo Ancelotti, ran riot over Russian side Rostov 5-0.

Joshua Kimmich grabbed a second-half double, with Robert Lewandowski scoring from the penalty spot, birthday boy Thomas Mueller and Spanish defender Juan Bernat giving Bayern early custody of Group D.

But only on goal difference as Atletico Madrid won 1-0 at PSV Eindhoven, Saul Niguez doing the damage with a sizzling scissor-style volley just before the break.

Ancelotti described his debut in Europe with the Bavarian giants as "a great game".

"Can we win the Champions League? For sure our team will be competitive this season and for the moment everything is good, but the first objective is to win the group, and then we will see the draw."

Napoli meanwhile may have lost their prolific goal-scoring machine Gonzalo Higuain after the Argentine jumped ship to Serie A rivals Juventus, but his replacement, Arkadiusz Milik, earned them a 2-1 win at Dynamo Kiev.

Denys Garmash put Kiev in front but Milik’s pair of opportunistic headers earned Napoli a key away success against a side that ended with 10-men.

Napoli sit top of Group B after Benfica were undone by one of their own players.

Franco Cervi sent the Portuguese side into an early lead against Besiktas but the Turkish visitors got an injury time equaliser courtesy of Talisca, loaned to Besiktas by Benfica last month.

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

The Spanish champions were fined €150,000 by UEFA because of the flags during last season’s competition.