Not since those glorious days of Lionel Messi in that famous blue-and-garnet shirt has Barcelona been this good.

This week, we’ll see just how good.

Ahead of what is always Barca’s biggest game of the season — the clasico against bitter rival Real Madrid in La Liga on Sunday — comes an eagerly anticipated trip to Paris Saint-Germain on Tuesday in the standout Champions League match of the third round.

It’s a meeting of the current top two in the nascent league-phase standings and, for many, an early taster 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’s title match 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 the likes of Lamine Yamal and Raphinha are fueling goal-fests every few days.

Barcelona has played 11 matches in all competitions this season, winning them all, and has 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 has set the standard in European soccer for the past two seasons?

PSG has 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 scorers 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 Barca in the ultimate test of its rejuvenation.

The PSG-Barca match will be going ahead as planned, the French government said Monday, despite violence and looting that occurred during weekend protests across the country.

Bayern-Arsenal is another high-profile match-up

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 match-up that pits another of Europe’s most devastating attacking units against the most well-organized defense on the continent.

Bayern, which has 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 has 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.

Emery con

tinues to work wonders at Villa

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

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

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

It’s a testament to the managerial skills of Unai Emery that Villa is riding high once again, having already won 3-2 at Club Brugge and thrashed Fenerbahce 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 wide-held status as, pound for pound, one of the best coaches in Europe is fully justified.

Haaland could get rested

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 woes

Italy’s problems at international level — shockingly, the men’s team hasn’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’s 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 for far. There’s been only one win, by Como.

All four are at home this week and they have benign fixtures on paper. On Tuesday, it’s Roma vs. Slovan Bratislava and Napoli vs. Bodø/Glimt; on Wednesday, it’s Como vs. struggling Manchester United and Inter Milan vs. Shakhtar Donetsk.