Barcelona: Lionel Messi, Luis Suarez and Neymar combined to devastating effect as Barcelona swatted Celtic aside 7-0 at the Nou Camp to lay down a marker in Champions League Group C on Tuesday.

Messi produced a stunning display, hitting a record sixth hat-trick in the competition. He smashed home a pass from Neymar in the third minute and the Argentine maestro struck again in the 27th after Celtic's Moussa Dembele had a penalty saved by goalkeeper Marc-Andre ter Stegen.

Neymar curled in a free-kick to stretch Barca's lead in the 50th minute before crossing for Andres Iniesta to volley the fourth. Messi then grabbed his third goal, overtaking Real Madrid greats Alfredo Di Stefano and Ferenc Puskas to reach six European Cup trebles.

Neymar laid on the sixth for Suarez and the Uruguayan completed the rout with his second strike in stoppage time.

Barcelona supporters, meanwhile, displayed 30,000 pro-Catalan independence flags at the start of the game, risking the wrath of Uefa.

In Munich, Bayern Munich crushed Champions League newcomers Rostov 5-0 with two goals from youngster Joshua Kimmich to kick off their Group D campaign and set a competition record with their 13th consecutive home victory.

The 21-year-old Germany international struck twice in the second half after striker Robert Lewandowski converted a 28th-minute penalty and Thomas Mueller added another goal on the stroke of half-time to kill off any chances of a Russian comeback.

Manchester City's opening Group C game against Borussia Moenchengladbach in Manchester was postponed following torrential rain at the Etihad.

An afternoon downpour was followed by persistently heavy rain, so referee Bjorn Kuipers and Uefa officials inspected the pitch and although it appeared to drain well after the rain relented soon afterwards, the game was called off.