Champions League: Lamine Yamal scores in Barcelona loss, Arsenal steals a point in Italy

Matchday 1 of the new, expanded and revamped UEFA Champions League first round concluded on Thursday with the final dozen participants making their debut in the 2024-25 version of soccer's most prestigious club competition.

Here are the biggest takeaways following Thursday's six-game slate.

Raya's saves salvage a point for Arsenal: Atléti snares late win

After reaching the quarterfinals last season — its first back in the Champions League after a five-year hiatus — and finishing as runner-up in England for two seasons running, Arsenal has designs on winning at least one of the two trophies in 2025. They were lucky to get even a single point at Atalanta on Thursday night.

Had goalkeeper David Raya not stopped Azzurri striker Mateo Retegui twice in quick succession in the second half, once from the penalty spot and again on the rebound, the Gunners would've left Italy empty-handed.

It looked as though Atlético Madrid would also settle for a tie — which wouldn't have been the worst outcome, even at home, after RB Leipzig scored four minutes into the contest Antoine Griezmann canceled that tally out, but the score was still even in the 90th minute. Fortunately for Atleti, Uruguayan center back José María Giménez nodded home the winner just as second half stoppage time was about to begin, sending the home crowd at Estadio Wanda Metropolitano into rapture:

Lamine Yamal scores, but early red card dooms Barcelona

It was probably always going to be a long night for Barcelona after defender Eric Garcia was shown a straight red card less than 10 minutes into Tuesday's trip to Monaco, and that was before the hosts pulled out to a 1-0 first half lead.

But Barça was in pretty good shape after star 17-year-old Lamine Yamal pulled his side level in the principality with a gorgeous equalizer — his first in the Champions League. 

The strike made Yamal the second-youngest scorer in tournament history after teammate Ansu Fati (Fati would enter off the bench later in the match), and Hansi Flick's team made it stand up late into the second half. Everything changed with just over a quarter-hour remaining, though, when Monaco substitute George Ilenikhena caught the Spaniards' back line sleeping and slotted what ended up being the game-winner past longtime Barca keeper Marc-André ter Stegen. It was Barcelona's first competitive loss under new manager Flick.

Bayer Leverkusen picks up right where it let off   

The German champions went almost all the way through the 2023-24 European season without a defeat, going unbeaten en route to the Bundesliga title and losing just the last match of their 51-game campaign — to Italian side Atalanta in the UEFA Europa League final.

Leverkusen has already dropped one Bundesliga contest this term. But having graduated to the Champions League this season, Xabi Alonso's side got off to a quick start in international play once again by spanking Dutch power Feyenoord 4-0 away from home on Thursday.

German national team striker Florian Wirtz opened the scoring in Rotterdam after just four minutes. Left back Alejandro Grimaldo doubled his team's advantage before Wirtz added Leverkusen's third well short of halftime.

An own goal before the break made it 4-0, and the visitors never looked back.

With its first domestic crown in history secured, Alonso can focus all his players' attention on making a deep run in European play next spring. With a trip to Bayern Munich looming at month's end and their next Champions League test against seven-time champ AC Milan, we'll soon see if they're legitimate contenders.

Doug McIntyre is a soccer reporter for FOX Sports. A former staff writer with ESPN and Yahoo Sports, he has covered U.S. men's and women's national teams at FIFA World Cups on five continents. Follow him @ByDougMcIntyre.