The Champions League rumbles on with Matchday 2 this week. Below, we dissect the biggest talking points from Tuesday's action in Europe's premier club competition.

Ten Hag, Man Utd hit rock bottom

There was no shortage of drama at the Theatre of Dreams on Tuesday. Unfortunately for Manchester United and manager Erik ten Hag, it was a repeat of the horror show that continues to derail their 2023-24 campaign.

In addition to their well-documented domestic struggles, Manchester United's hopes of progressing beyond the opening round of the Champions League took a hit after losing in dramatic fashion to Galatasaray at Old Trafford, a defeat that leaves Ten Hag's men last in Group A.

There were numerous points of encouragement for the hosts Tuesday when it seemed Manchester United were destined to come away with a valuable victory. It might have helped to temporarily subdue calls for Ten Hag's dismissal amid Manchester United's historically bad start in the Premier League.

Instead, those grumblings have grown louder. Manchester United were their own worst enemy, blowing a pair of one-goal leads before allowing the Turkish side to get its first-ever win on English soil.

Aside from Rasmus Hojlund's inspired two-goal performance, it was the same old story for the struggling Red Devils. Poor defending, wasted opportunities, and a lackadaisical attitude contributed to Galatasaray's most famous win on a night that might be looked back on as rock bottom for Ten Hag's tenure at Manchester United.

The defense was a mess again, while Andre Onana produced another worrying performance to compound his miserable start at Manchester United. Then, with the game tied late on, United pushed forward for the go-ahead goal, only to see Galatasaray go the other way and score the winner courtesy of Mauro Icardi, whose clever chip over Onana helped avenge his penalty miss just minutes before.

In a last-ditch attempt to get something from the game, Ten Hag introduced Antony, even though the Brazilian hadn't played a minute in almost a month due to an ongoing assault investigation. Predictably, Antony didn't look sharp.

With Manchester United tasting defeat for the sixth time in all competitions - the most losses after 10 games since 1986 - will Ten Hag even be around to oversee the club's next Champions League match against Copenhagen?

Madrid's midfielders run the show

There was a lot of talk about Real Madrid's inability, or unwillingness, to spend big on a replacement for Karim Benzema this summer. Critics couldn't understand why they'd enter the season with Joselu as their only recognizable center-forward.

But the conversation seemed to overlook the goal-scoring potential of Madrid's gung-ho midfielders, a group that again proved its versatility in Tuesday's swashbuckling 3-2 win over Napoli.

Jude Bellingham and Federico Valverde were each involved in eight attacking sequences, as many as Vinicius Jr. and more than any other player on the pitch, and Eduardo Camavinga, playing again at left-back, joined the attack whenever he could. Bellingham created the first goal with an interception in the final third and scored for the eighth time in nine games off an incredible solo run that made Napoli's defenders backpedal like politicians under controversy. Valverde patrolled the right flank, taking up, as he usually does, various defensive and attacking roles, and when Madrid were probing for a winner, the Uruguayan, one of the game's great long-distance specialists, uncorked a spectacular half-volley deserving of the two deflections it took en route to goal.

Luka Modric contributed off the bench as well. The 38-year-old restored Madrid's equilibrium just as Napoli threatened to knock them completely off balance. The Serie A champions had just leveled and the game was threatening to become a track meet. In just 25 minutes, Modric shut Napoli down, forcing them to shoot from distance.

That Madrid can even summon such a level-headed and experienced player off the bench is unfair. With that kind of midfield depth, expect Los Blancos to make another deep Champions League run.

Arteta pays price for Saka gamble

Arsenal's second Champions League game couldn't have gone much worse.

Along the way to dropping three points in an away defeat to Lens, Arsenal were dealt a blow that could have massive consequences going forward. Bukayo Saka's removal from the contest due to an apparent leg injury proved to be a pivotal moment and one that may not have even been necessary.

Arteta elected to start the 22-year-old despite his recent injury concerns rather than play it safe just days before what's undoubtedly Arsenal's biggest match of the season against Premier League rivals Manchester City.

The bet looked like it might pay off after Saka set up Gabriel Jesus' opening goal with his fifth assist in all competitions. But his evening was over 20 minutes later after going down to receive treatment for a non-contact injury. It was the third game in a row that Saka was forced off.

Arteta revealed after the contest that Saka injured himself on a backheel pass, adding that he had "no clue" about the winger's availability for Sunday's game in north London. Saka's durability provides a glimmer of hope, but that doesn't hide the fact that Arteta's gamble on his best player's fitness backfired at the worst possible time.

Lens deserve a ton of credit after securing their first Champions League win in 21 years with a positive attacking display. But Arsenal were ultimately undone after failing to strike a cohesive balance in their attack after Saka's removal.

With Saka trending toward joining the injured Gabriel Martinelli on the sidelines, Arteta will need to hash out an effective game plan and inspire his men to defy the odds against his former employers, Manchester City. Only three points Sunday can smooth over the bitterness of Tuesday’s deflating loss.

Quick free-kicks

Another harsh lesson for Union Berlin

Anticipating a huge turnout for their first foray into the Champions League, Union Berlin decided to host their group stage matches at the Olympiastadion, the home of city rivals Hertha Berlin. The party swelled to over 70,000 people on Tuesday and turned to revelry when Sheraldo Becker gave Union an early 2-0 lead over Braga. Row upon row of fans clad in their sacred red attire bounced up and down.

But the celebration turned to agony in the second half, with Braga erasing the deficit before scoring the winner in the 94th minute. The German upstarts haven't played badly in the Champions League - they held Madrid goalless for 93 minutes in their opening match - but again learned a harsh lesson. They were powerless to stop Bruma's outrageous curling effort earlier in the second half but naive to let a low shot skip past them deep into stoppage time.

Bayern still a work in progress

Bayern Munich needed a goal from teenage substitute Mathys Tel to extend their winning streak in the Champions League group stage to 15 matches. Before that, they toiled mightily against Copenhagen's tight-knit defense, creating few genuine chances - despite controlling as much as 65% of possession - and going nearly the whole first half without a shot on target.

Tel's winning goal - which closely followed Jamal Musiala's equalizer - wasn't even the byproduct of the smooth passing sequences fans have come to expect from the serial Bundesliga champions. Goalkeeper Sven Ulreich hoofed the ball forward, Harry Kane nodded the ball into Thomas Muller's path, and Muller bought enough time for Tel to join the attack and fire home. It was a broken play and a rare buckle in Copenhagen's stronghold that created the breakthrough, not a play Bayern had developed on the training pitch.

Stat of the day

Will Bayern Munich's group stage superiority finally pay off?

Tweet of the day

Lens gave Europe another reason to take Ligue 1 seriously.