Before Sunday's El Clasico against rival Real Madrid, Barcelona faces an eagerly anticipated trip to Paris Saint-Germain Tuesday in the highlight match of the Champions League's third round.

It's a meeting of the current top two in the nascent league-phase standings and, for many, an early preview of what could easily be the lineup in the final, which is being staged in Madrid next June.

That would underline the definitive revival of Barcelona, which hasn't been in the Champions League final since 2015 – when Luis Enrique, the current PSG coach, was at the helm and Messi was wreaking havoc in that prolific front line alongside Neymar and Luis Suarez.

More than a decade later, the names aren't quite as stellar – not yet, anyway – but Lamine Yamal and Raphinha are fueling goal-fests every few days.

Barcelona have played 11 matches in all competitions this season, winning them all, and have scored 48 goals already. That's more than 4.3 goals a game.

Can that continue against PSG, the defending two-time champion and the team that have set the standard in European football for the past two seasons?

PSG have found its groove in recent weeks, too, winning six games in a row including two straight in the Champions League – 6-1 at home to Slovan Bratislava and 4-2 at Manchester City last week. That makes them the top scorer in the competition, with one more goal than Barcelona after its 5-1 win over Feyenoord and 4-1 victory at Galatasaray.

A year ago, PSG came to Barcelona in the league phase without injured star forwards Ousmane Dembele, Désiré Doué and Khvicha Kvaratskhelia and rallied to win 2-1, with Goncalo Ramos scoring a 90th-minute winner.

Revenge would be sweet for Barcelona in the ultimate test of its rejuvenation.

If PSG and Barcelona are currently the best two teams in Europe, Bayern Munich and Arsenal aren't far behind.

They meet in Munich in another stellar matchup that pits another of Europe's most devastating attacking units against the most well-organized defense on the continent.

Bayern, which have four points from a possible six in the Champions League so far, is coming off a 6-1 win over Leipzig in the Bundesliga that makes it 36 goals in 10 games this season.

Arsenal have yet to concede a goal after back-to-back wins in Europe and is tied for the best defensive record in the Premier League with five goals conceded in seven games.

Questions are being asked, though, about Arsenal's attacking strength under Mikel Arteta, who said after last season's penalty-shootout loss to PSG in the final that his team needed to show more ambition to "reach another level."

At the moment, it looks like Arteta is back to relying on his mean defense to get results. On Wednesday, it will have to stop Harry Kane, the former Tottenham striker who has scored a competition-high 17 goals in the Champions League since the start of last season.

Don't be surprised if Aston Villa tops the Champions League standings come the end of the third round of games.

The English club are one of nine teams on a maximum six points and is in third place, with the same +7 goal difference as PSG and Barcelona.

Villa have a kinder fixture, though, at home to Norwegian team Viking.

It's a testament to the managerial skills of Unai Emery that Villa are riding high once again, having already won 3-2 at Club Brugge and thrashed Fenerbahçe 6-0.

Emery lost the spine of his team over the summer with the departures of Emi Martinez, Ezri Konsa, Youri Tielemans, Morgan Rogers and Ollie Watkins but has fashioned a new lineup, spearheaded by Nicolas Jackson and exciting Swiss midfielder Johan Manzambi.

Emery's widely held status as, pound for pound, one of the best coaches in Europe is fully justified.

Manchester City might have to press pause on Erling Haaland's stunning Champions League scoring exploits.

The striker, who has 61 goals in just 60 games in the competition, hobbled off the field after the 3-2 win over Ipswich in the Premier League on Saturday. That was his third straight game after a period of international duty with Norway that ended with Haaland asking to be substituted with fatigue.

A home match against AEK Athens seems the ideal opportunity for City manager Enzo Maresca to give his star player a rest.

Italy's problems at international level – shockingly, the men's team haven't qualified for three straight World Cups – are well-known.

It's not going great at club level, either.

Only one Italian team reached the Champions League round of 16 last season – and Atalanta got thumped 10-2 on aggregate by Bayern there – and the nation's four representatives (Inter Milan, Napoli, Como and Roma) this season have lost six of their combined eight games so far. There's been only one win, by Como.