Matchday Five is normally the round of the group stage in which top spots are consolidated, and second places sealed up. Not so Tuesday, which saw late drama in Manchester force a three-way tie in Group E. There was also a record-breaking hat trick in Cyprus and a goalscoring return to action for Zlatan Ibrahimovic. This is what caught our eye:
Players of the Day: Sergio Aguero (Manchester City) and Lionel Messi (Barcelona)
The two Argentine strikers each netted hat tricks, both significant in their own way. Manchester City was facing a near-impossible task to qualify on Matchday Six until two Aguero goals in the last five minutes turned a 1-2 deficit into a 3-2 win over 10-man Bayern Munich.
It still won't be easy but City captain Vincent Kompany summed it up best after the game: "If you want to succeed at anything, you need a special player in special form and Sergio is that; he makes things achievable that otherwise wouldn't be."
Messi also scored a hat trick, his second in four days. That will overshadow Luis Suarez's first goal for his club, a smart turn on the edge of the area and curled shot to give Barcelona its first in a 4-0 win at APOEL Nicosia. For his first, Messi diverted Rafinha's shot to become the Champions League's leading goalscorer. He overtook Raul, on 71, with a Raul-esque goal, and added two more in the second half.
That put him on 74, three ahead of Cristiano Ronaldo, who no doubt will look to score a hat trick Wednesday against FC Basel.
Goal of the Day: Nani (Sporting Lisbon)
The renaissance of Nani back at his former club Sporting Lisbon has flown under the radar outside of Portugal, but with four Champions League goals this season, it's becoming hard to ignore - especially if you are a Manchester United fan crying out for some guile in wide positions.
When Louis van Gaal sent Nani on loan to Lisbon, he was all set to play a 3-5-2 system which had no room for wingers; now, though he has changed to a 4-2-3-1, and Nani, on this form, would thrive.
He scored Sporting's second in its game against Maribor, an absurd goal that was reminiscent of this video of Shinji Kagawa and Hiroshi Kiyotake dribbling their way around 55 Japanese schoolkids before scoring. For Nani, it was more like six Maribor defenders, but every time they blocked his shot, he dribbled past two more and shot again - until he scored.
"I think I needed a little time away [from Manchester United] to understand and find my confidence again," Nani was quoted as telling the Portuguese press last week. "Louis van Gaal gave me the option to go. I could have stayed but I chose the best option for me at the time and I think I was right. I am enjoying my football again now."
And if United wants him back at Old Trafford in the January transfer window, it is set to be disappointed: there is no recall clause in the deal, despite his salary being almost entirely covered by United. No wonder Sporting wants to hold onto him.
Major Takeaway of the Day: We will need calculators on Matchday Six
Group E goes to the wire with Roma, Manchester City and CSKA Moscow all tied on three points. The reason? Vasili Berezutski's last minute goal for CSKA to secure a draw against Roma in the early kickoff. That means that any of the trio could qualify for the next round.
Here are the permutations: if CSKA loses to Bayern Munich, Manchester City will qualify with any scored draw or win over Roma. A 0-0 draw or home win will put Roma through. If CSKA draws or wins at Bayern, then it will go down to head-to-head between the two sides level on points; which means we will need our calculators at the ready.
It's also worth mentioning that Bayern had done brilliantly for 65 minutes playing with 10 men, scoring two goals in quick succession, neither of which made Joe Hart looking good (mind you, nor did his mustache). The Aguero late show changed everything - including, perhaps, City's whole relationship with the competition.
Surprise of the Day: Chelsea shows no mercy for Roberto Di Matteo
Chelsea fans gave their former boss Di Matteo a standing ovation in his first European home game in charge of Schalke since leading Chelsea to victory in the 2012 Champions League final. Jose Mourinho talked down Di Matteo's achievement pre-match with the reminder that Chelsea had finished fifth in the league - when Mourinho won his two Champions Leagues with Porto and Inter, his sides won the league - and Mourinho clearly told his players to show no mercy to Di Matteo in Gelsenkirchen.
Chelsea won 5-0 and the host could not have been more accommodating: from failing to mark John Terry for his early headed goal, to goalkeeper Ralf Fahrmann allowing Willian's shot to squeeze in at his near post, to Jan Kirchoff's needless own goal before halftime.
Chelsea pushed on in the second half, and two men crucial to the 2012 success, Ramires and Didier Drogba, scoring. You sense that if Mourinho enjoyed it, the players might have had some sympathy for their former coach, who is already under pressure.
Late Twist of the Day: CSKA takes points away from Roma
The biggest twist came in the earliest game, with CSKA defender Berezutski's hopeful cross, the last kick of the game, sailing past everyone, including Roma goalkeeper Morgan de Sanctis. Instead of a win putting Roma in favorable shape to go through, the Italian side needs things to go its way against Man City in the group finale.
But there was also some late drama in Group F, in which Paris St.-Germain needed two late goals from Edinson Cavani and one from Zlatan Ibrahimovic, with a typical shot out of nothing, to overcome Ajax 3-1. That puts PSG top of the group ahead of its trip to Barcelona; a draw will be enough to keep it there.
That tie will be fascinating, with Ibra fit again and back at his former club, just at a time when Barcelona looks to be clicking into form again. Considering all eight group winners advanced to the quarterfinals last year, there will be plenty on the line at Camp Nou.
Manchester City 3, Bayern Munich 2
CSKA Moscow 1, Roma 1
APOEL 0, Barcelona 4
Paris St.-Germain 3, Ajax 1
Schalke 0, Chelsea 5
Sporting Lisbon 3, Maribor 1
Shakhtar Donetsk 0, Athletic Bilbao 1
BATE Borisov 0, Porto 3