The 2023–24 UEFA Champions League group stage returned on Tuesday with eight games to start Matchday 2 following a week off.

Here are the top five lessons learned:

The finest aim yet for Bellingham

Jude Bellingham was already off to a record-breaking start at Real Madrid, having scored seven goals in his first eight games. This was especially true going into Tuesday's highly anticipated, big away match against Serie A champions Napoli.

The 20-year-old Englishman kept up his scoring spree in Italy, netting his eighth goal in the most spectacular way possible with a slaloming run past multiple players, a cut-back, and a right-footed finish past goalie Alex Meret.

The 14-time European champions were ahead 2-1 after to a goal from Bellingham; the hosts had taken the lead early on with to a goal by Leo Skiri Østigård of Napoli, but Vinicius Junior equalised it. Real would have won the game with a third. Rather, a VAR check resulted in a Charmin-soft penalty for the Neapolitans. By converting it, Piotr Zieliński denied Bellingham what would have been a deserving victory of the match. 

Real Madrid was able to return to the Spanish capital with all three points, though, thanks to a late own goal by Meret, which came after Federico Valverde's lightning-fast drive that struck the crossbar, the keeper, and the goal itself. The match more than lived up to expectations.

Saka's injury overshadowed Arsenal's loss

When Arsenal travelled to Lens in France, things got off to a wonderful start. Following a resounding victory against PSV Eindhoven on Match Day 1, the Gunners seized the lead early at Stade Bollaert-Delelis thanks to Gabriel Jesus. But after that, everything fell apart.

First, Adrien Thomasson's incredible curling goal gave the hosts an equaliser. Then, after just 34 minutes of play, Arsenal's outstanding forward Bukayo Saka was pulled off the pitch due to a non-contact injury.

With almost 20 minutes left in the second half, Elye Wahi finally broke the tie for the home team, and the game concluded 2-1. It was awful enough to blow a lead and go away empty-handed, but the idea of missing Saka for an extended period of time is much more daunting. Mikel Arteta, the manager of Arsenal, stated that the injury is significant after the game. That means the Gunners suffered two losses on Tuesday.

Casting Once more, Manchester United startled at home.    

Galatasaray hadn't even managed an away goal in the Champions League in twenty games. The Turkish team defeated Man United 3-2 at Old Trafford on Tuesday, earning three points in the process, leaving the Red Devils without a point after two group stage matches.

Even worse, the final 20 minutes of the rain-soaked match saw the visitors score their final two goals. As he covered the game for the official broadcaster, United icon Peter Schmeichel said, "Not acceptable," right away from the pitch. "The mistakes being made are simply not good enough."

Erik ten Hag's squad bounced back from a loss to Bayern Munich in Germany two weeks prior with victories in the Premier League and EPL Cup. However, the setback on Tuesday followed another heartbreaking home loss to Crystal Palace in the Premier League on Saturday. It wasn't a coincidence either, as Mauro Icardi missed a penalty kick for Galatasaray before to scoring the game-winning goal. 

The good news for Red Devils fans is that the team will play two of its next three games at home, including a Champions League matchup against FC Copenhagen on October 24. If Ten Hag loses that one, it will undoubtedly be the end for him, presuming the coach is still out in three weeks.

In Copenhagen, Bayern gets all it can bear.

Bayern was anticipated to travel to Denmark's capital in the middle of the week and win all three points, since they are a consistent challenger for trophies. That's what ultimately transpired, but the hosts sure as hell made the German heavyweights fight for their victory.

After halftime, FC Copenhagen took the lead thanks to a goal from Lukas Lerager ten minutes later. At that moment, Bayern's supporters were perspiring. However, it wasn't long before things were back to normal, as goals from Mathys Tel and Jamal Musiala in the last 30 minutes kept Tomas Tuchel's team unbeaten two games into the current Champions League campaign: