Champions League draw: Guardiola derby for Barcelona and City, Bayern meets Atletico

The 32 teams involved in this season's Champions League learned their group stage opponents on Thursday, as the draw for the opening round of the competition took place in Monaco, offering up some colossal encounters.

The headliner sees Pep Guardiola return to the Camp Nou, as Barcelona was drawn alongside Manchester City in what promises to be an engrossing clash that will signal just how quickly the Citizens have been transformed under the Spanish tactician.

Group C also boasts Borussia Monchengladbach, who will be looking to spring an upset alongside Celtic.

The draw also offeres up a rematch of last season's semi-final, as Bayern Munich will renew hostilities with Atletico Madrid.

(Courtesy: UEFA)

Here's a look at how the eight groups stack up:

Group A

Paris Saint-Germain, Arsenal, FC Basel, Ludogorets

Paris Saint-Germain and Arsenal will be the overwhelming favourites to emerge from Group A, with FC Basel and Ludogorets likely coming out of the pot to significant sighs of relief from supporters of both the French and English behemoths.

Group B

Benfica, Napoli, Dynamo Kyiv, Besiktas

Napoli was among the biggest winners from Thursday's draw, the Italian side avoiding the proverbial powerhouses that were lurking in Pot 1. That said, trips to Ukraine and Turkey are always tricky, and will need to be maneuvered with care.

Group C

Barcelona, Manchester City, Borussia Monchengladbach, Celtic

The obvious showstopper.

Pep Guardiola's return to the Camp Nou, where he won everything on offer and established himself as the innovative genius that he is today, will garner all the attention.

Can Borussia Monchengladbach and Celtic cause a stir and disrupt what conventional wisdom says should be a clear top two?

Group D

Bayern Munich, Atletico Madrid, PSV, FC Rostov

A rematch of last season's semi-final beckons between Bayern Munich and Atletico Madrid, while PSV and FC Rostov are, frankly, just here to make up the numbers.

Group E

CSKA Moscow, Bayer Leverkusen, Tottenham, AS Monaco

The most wide-open section in the competition will see four sides each with an equal belief that they can reach the knockout stage. It may not garner the attention of the other groups, but it's sneaky good.

Group F

Real Madrid, Borussia Dortmund, Sporting Lisbon, Legia Warsaw

A meeting between Pierre-Emerick Aubameyang's current club and his favourite childhood side is being somewhat overlooked amid all the other storylines, but those two contests should promise plenty of goals.

Group G

Leicester City, FC Porto, Club Brugge, FC Copenhagen

Football's Cinderella side will have watched the draw unfold with an enormous smile, as Leicester City was easily the big winner on the day.

Portuguese powerhouse FC Porto will certainly fancy its chances of challenging the Foxes for top spot - and should be favoured to do just that - but there's no reason Claudio Ranieri's men shouldn't reach the knockout stages of the tournament.

Imagine saying that at this time last year.

Group H

Juventus, Sevilla, Lyon, Dinamo Zagreb

Another sneakily intriguing grouping.

While Juventus is the obvious juggernaut and will be expected to top the section, three-time reigning Europa League kingpin Sevilla will prove a stern test - as was the case when the two clubs were paired together at this stage last season - while Alexandre Lacazette can win matches single-handedly on his day for Lyon.

The first matchday of Europe's showpiece competition is slated for Sept. 13 and 14.