Champions League Matchday 5 saw its first eight matches played on Tuesday, with 27 goals being scored. It was an eventful day where Barcelona won its group and Bayern Munich clinched a spot in the knockout stages. Here are the results and three things to know.

1. Barcelona with Messi back, unstoppable?

That's 10 goals in two games since Lionel Messi returned from injury, and he has looked sharp. The Argentine superstar scored twice for Barca on Tuesday in its 6-1 win, grabbing a nice chip and an easy tap in. Without Messi, Barca had looked great since his September knee injury, sitting in first place in La Liga and in its Champions League group. But with Messi, this team looks close to unstoppable. Opposing teams have not serious attempted to pressure, to be extra physical and to try to frustrate the Barca attack. And if you can't do that, you have little chance with how quickly the team moves the ball. Barca could well be on its way to back-to-back trebles, and Tuesday was an example why.

2. Arsenal in better shape than we thought.

After being out six points entering the matchday, it looked like Arsenal had no chance of qualifying. But now, a win against Olympiacos on the last matchday will see the Gunners advance to the knockout stages. Momentum is back with the 3-0 win over Dinamo Zagreb. Is Arsene Wenger pulling his usual magic? But now, going on the road to Greece is a tough task. And with all the injuries, Arsenal will have to be in top form. But a win against Bayern Munich earlier in the competition proves that this team can do it.

3. Chelsea back from the dead?

Break Chelsea up! That's consecutive wins for just the second time this season, and Chelsea is sitting in Group G with 10 points, tied for first and two points above the third-place spot. Now, it was just a 4-0 win over Maccabi Tel Aviv days after a win against Norwich at the weekend, so it hasn't been against top competition. But it's a start to the turn around Blues fans are hoping for.

Messi
A magical night for Messi and Barca. (Getty Images)