Biggest takeaways, questions after 1st leg of Champions League semis

We're at halftime of each Champions League semifinal tie. Here's what we've learned from the first legs - and what each team must do to book their ticket to the final in Munich.

Arsenal vs. Paris Saint-Germain

PSG lead 1-0 on aggregate
Second leg: May 7 (Parc des Princes)

Key takeaway from 1st leg

Luis Enrique's PSG are unlike any other we've seen in the Qatari era. There's complete buy-in from every player and a wholehearted commitment to pressing the opponent. The most talented players on the field work hard off the ball and attack spaces like their lives depend on it. The team isn't just a collection of individual players anymore. It's a cohesive unit with an identity and selfless streak that previous managers couldn't quite coax out of the many superstars who passed through the doors at the Parc des Princes.

Ousmane Dembele, who scored the go-ahead goal in the fourth minute Tuesday, only had 30 touches because he was chasing runners all over the field. Desire Doue, a 19-year-old attacking phenom whose snap shot from close range almost delivered the visitors a 2-0 lead, was as active in PSG's half as he was in Arsenal's. Joao Neves and Fabian Ruiz got out of tricky spots and motored up and down the field as de facto midfield bodyguards.

When they have the ball, PSG are so sure of themselves. They often bypassed Arsenal's press like it was child's play, showing complete faith in their ball-playing ability to find solutions in real time. They made 26 passes before Dembele's goal. That's their system at work. For so long, they didn't have much of a system at all.

Arsenal tried their best to navigate PSG's high-energy attempts to win the ball, but they clearly missed Thomas Partey, the press-resistant midfielder suspended for yellow card accumulation. Partey would've made it much easier for Arsenal to move the ball in a more meaningful direction. They also missed someone like Kai Havertz, the space-invading forward who so often provides an outlet under pressure. While Partey is set to return for next week's second leg, Arsenal won't have Havertz back from injury. It'll be up to midfielder Mikel Merino to shape-shift once again and hold up play a little better than Leandro Trossard could manage up front.

Biggest question going into 2nd leg

Can Arsenal find a breakthrough? While they created a couple of clear-cut chances at the Emirates, forcing Gianluigi Donnarumma into a pair of stunning diving saves, the Gunners were largely ponderous in the attacking half. Arsenal almost always looked to make the perfect pass before even thinking about pulling the trigger, and it resulted in a lot of the sideways variety.

Bukayo Saka and Gabriel Martinelli lost pace and precision after poking serious holes in PSG's defense in the opening 45 minutes. Trossard, Arsenal's stand-in center-forward, finished the game with just four touches in the penalty area. Arsenal couldn't even get their free-kicks quite right - and that's their bread and butter.

Credit must go to PSG's backline and midfielder Neves, whose inch-perfect tackles broke up Arsenal's promising plays. But the north London side must also have an answer for its inefficient play and take the game by the scruff of the neck. - Anthony Lopopolo

Barcelona vs. Inter Milan

Tied 3-3 on aggregate
Second leg: May 6 (San Siro)

Key takeaway from 1st leg

Styles make fights. The classic boxing idiom is a perfect descriptor for this clash between two teams, and, frankly, two clubs, that are polar opposites in nearly every meaningful way. Barcelona, littered with youth, exuberance, and homegrown talent, went into Wednesday's match with the most potent attack in the tournament. Inter, savvy market operators whose starting lineup was the oldest any side has named for a Champions League semifinal since 2017, arrived in Montjuic with the stingiest backline in the competition. The former wanted to control possession, dictate tempo, and keep the visitors under constant pressure. The latter, meanwhile, wanted to stay compact, absorb that pressure, and then strike like lightning on the counter.

Both succeeded, and it made for one of the best games of the season so far.

Inter were ruthlessly efficient, scoring with all three of their shots on target. They used their superior size to pick Barcelona apart from set pieces; the Italian side has now scored 15 goals from corners in all competitions this season. Denzel Dumfries, who netted both of them in Montjuic and set up Marcus Thuram's opener 30 seconds into the contest, torched Barcelona's infamous high defensive line to the point where it was comical, bordering on nonsensical, to see Hansi Flick's team stick with the tactic. Dumfries was enjoying himself so much down the right wing that he was visibly annoyed when he was substituted.

Barca, who had 66% of the ball and attempted 19 shots, showcased all the slick passing and intricate combinations that have made them one of the most aesthetically pleasing teams in the world to watch. There were gorgeous passages of play where Inter were chasing shadows as Frenkie de Jong and the irrepressible Pedri pulled the strings, turning opposing midfielders inside out and slicing down the middle and into the box despite often facing a wall of 10 defenders. Barca's naivety was exposed by Inter - not falling asleep right from the opening kickoff in the second leg would be a good place to start - but they deserve praise for staying calm and battling from behind against a team that doesn't often squander a lead, let alone two within the same match.

Much of that credit goes to Lamine Yamal, who's already so absurdly good at 17 that it belies belief. His skill on the ball is bewitching - Federico Dimarco was put through the wringer trying to mark him, and Henrikh Mkhitaryan didn't fare much better when doubling up on the teen phenom. But what's more impressive is the way the youngest player on the pitch took over the game when his team needed him most, single-handedly dragging Barca back into the contest with a brilliant solo goal after Inter took an early 2-0 lead. Yamal probably scared Barca fans half to death when he pulled up in the prematch warmup with an apparent groin issue. Still, he was a constant threat, hitting the crossbar twice. He's now played 100 senior matches for Barcelona, amassing 22 goals and 33 assists in that time. In case a reminder is needed: This isn't normal.

"Yamal is a phenomenon of the kind born every 50 years," Inter boss Simone Inzaghi opined after the match. How do you stop a generational talent? That's for him to figure out ahead of the second leg.

Biggest question going into 2nd leg

How quickly can the various injured players on either side recover? Robert Lewandowski and Alejandro Balde missed the match for Barcelona, and their absences were certainly felt. Ferran Torres, who continues to start in Lewandowski's absence, scored a goal but spurned at least one other good opportunity. He wasn't able to get into open space - the one area where he's better than Lewandowski - because Inter set up shop sitting so deep.

Balde's recovery pace was badly missed at left-back, where Gerard Martin kept getting exposed trying to keep up with Dumfries. Inter's tried-and-true tactic isn't overly complex, but it's damn effective. Lautaro Martinez and Thuram combine after a long pass forward - one wins the initial ball, and the other brings a midfielder, often Nicolo Barella, into the play. The ball then quickly gets fired out to the far wing, where Dumfries or Dimarco races forward depending on which side of the field the play originated. That's how Inter kept carving Barcelona open, aided by the inviting high defensive line.

Balde's possible return could help mitigate that somewhat, though Jules Kounde on the other side is also now a doubt for the return fixture. Martinez's injury status could also play a huge role. The Inter captain left Wednesday's match at halftime with an apparent leg injury, and Inzaghi admitted he's a doubt for the second leg. None of Mehdi Taremi, who replaced him, Marko Arnautovic, or Joaquin Correa can replicate the Argentine's smart combination play with Thuram. If he's unavailable next week, it makes Inter's attack much more one-dimensional. - Gianluca Nesci