The first matchday of the the 2017 UEFA Champions League group stage is in the books and it featured some fantastic performances by Europe's best teams and players. Lionel Messi finally got one over on Gianluigi Buffon, PSG's Big Three all got on the scoresheet, and Manchester United won big despite an injury to Paul Pogba.

Messi finally scores on Buffon

The marquee game of the Champions League's first group stage matchday of 2017 was the contest between Barcelona and Juventus at the Camp Nou. As always is the case when these two clubs meet, the story of the contest was Lionel Messi vs. Gianluigi Buffon.

Entering the match, Messi had never scored on Buffon. But the world's greatest player broke his duck against the world's greatest keeper with a goal in the 45th minute to help propel Barcelona to a 3-0 win.

And what a deceptively fantastic goal it was. Messi played a one-two with Luis Suarez at the top of the box on a Barca counter before firing past Buffon for the 1-0 lead. The Italian keeper didn't even attempt a dive. Messi fired his shot a split second before most players would attempt one from that position, and it froze Buffon to his spot. In this battle between unstoppable force and immovable object, unstoppable force won.

Ivan Rakitic scored in the 56th minute to give Barcelona a 2-0 advantage and put the result fairly out of doubt.

With one finally in his account against Buffon, Messi didn't wait long to double it. He scored again in the 69th minute to give Barcelona a 3-0 lead against one of the best defenses in world soccer. Doubts about Barcelona that surfaced after a poor showing in the summer transfer window evaporated with this lights-out showing.

PSG's Big Three find the back of the net

Paris Saint Germain/Qatar broke all transfer records to sign Neymar and Kylian Mbappe for one reason alone: to win the Champions League. There's still a long way to go before they accomplish that goal, but PSG got off to a flying start in this year's tournament with a 5-0 win over Celtic.

The Parisians' victory was powered by an attacking masterclass from its trio of superstar strikers: Neymar, Mbappe, and Edinson Cavani all scored first half goals to end Celtics' hope for a result early.

Neymar was the first on the scoresheet, nabbing his fifth goal in as many matches for PSG by beating his man on the counter and blasting a shot past the keeper for the 1-0 lead. He then ran to corner to celebrate with Mbappe and Cavani, a sight we're sure to see many times over the next few years.

Mbappe got his goal next, and it came via an assist from Neymar. In the 34th minute, a cross swung in from the right flank to Neymar at the far-post. Instead of putting a shot on goal, Neymar glanced a header down and square with goal to Cavani. Cavani whiffed on his shot, but Mbappe was in perfect position to pounce and bring the score to 2-0.

Although he missed a chance on the eventual Mbappe goal, Cavani was still able to get his. Five minutes before halftime, the Uruguayan attacker nailed one from the penalty spot to give PSG a 3-0 lead. Cavani added another in the 85th which -- along with an own goal from Mikael Lustig -- gave the final 5-0 scoreline.

The attacking triumvirate of Neymar, Mbappe and Cavani also all scored in their Ligue 1 debut last week. It's safe to assume this will not be the last time all three get on the scoresheet in the same game.

Manchester United wins, but loses Pogba to injury

Manchester United received a big scare during its 3-0 win over FC Basel in its return to Champions League play. Less than 20 minutes into the match, midfielder Pogba was forced off with what appeared to be a hamstring injury.

The good news for United was that his replacement, Marouane Fellaini, scored with a towering header about 15 minutes after coming onto the pitch.

And what is a Manchester United game these days without a goal from the club's new talisman, Romelu Lukaku. The Belgian striker continued his fantastic run of form with United by scoring his fifth goal in as many games for the club since the start of the English Premier League season on a header in the second half. Marcus Rashford added a third in the final 10 minutes to get the 3-0 scoreline.

Full Champions League results

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Cy Brown writes about football, golf, soccer and other stuff for Sports on Earth. Follow him on Twitter @CEPBrown.