At last the cycle is broken. Olympiakos became the first side that finished second in its group to take a lead in its Champions League round of 16 first leg tie, with an impressive 2-0 win over Manchester United. In the other tie, last year's runner-up Borussia Dortmund beat Zenit St. Petersburg 4-2.
Here are some highlights from another compelling round of action:
Player of the day: Alejandro 'Chori' Dominguez, Olympiakos
"Show me your No. 10, and I will tell you how your team plays," said Olympiakos coach Michel, quoting a phrase popular in Spain, in an interview with So Foot magazine earlier this season. His comment summed up the key moments of his team's win over Manchester United - and in particular the comparison between Wayne Rooney, United's No. 10 and Dominguez, wearing No. 35 but playing the same role for the Greek champion.
The two men almost trod on each other's toes in the first half, so deep was Rooney dropping back to win the ball, or even get close to it. In the same space, Chori was pouncing on everything and, eight minutes in, almost opened the scoring, with a blistering 20-yard run through the middle of a United defense that opened up for him. Only a last-gasp lunge from Nemanja Vidic denied his shot from eight yards.
As the first half continued, United rarely threatened and when Olympiakos did, Chori was usually involved. When, just before halftime, he flicked in Giannis Maniatis's shot from outside the area with his heel, it looked like he knew what he was doing. If his celebration looked like a huge release of emotion, it was: no other player on the pitch has had a roller-coaster career like his. A Russian title winner with Zenit in 2007, he was dropped for the victorious UEFA Cup final in 2008, and, after considering quitting the game, left Zenit and won the Russian title again with Rubin Kazan.
A failed spell with Valencia followed, then a loan spell back home at River Plate (and a fall-out with president Daniel Passarella) before last season, he helped Rayo Vallecano stay up in La Liga.
This is his first season in Greece and he is the league's leading assist-maker. Since the sale of Kostas Mitroglou to Fulham -- a sign, some Olympiakos fans thought, that the club had written off its chances of getting past United -- Olympiakos has kept on scoring (14 in its last three league games). Chori, 32 but never capped by Argentina, has been at the heart of it.
"I like my players to surprise me," said Michel, "because if they manage to surprise me, it means they will surprise the opponent. I love spontaneity and risk-taking in my players."
Chori embodied that spirit against United.
Moment of the day: Joel Campbell scores Olympiakos' second
The goal itself could prove to be a decisive one in this tie -- after all, a 1-0 away defeat is surmountable, but 2-0 makes life difficult in the second leg -- but it was more what it represented that will send shockwaves around Europe in the aftermath of the first surprise result of this season's Champions League knock-out round.
United was poor in the first half, was playing very defensively and seemed happy enough to leave Athens with a 0-0 draw. When Chori broke the deadlock before the break, you expected a reaction from the United players in the second half; but there was nothing, and the nature of the second goal summed it up.
Tom Cleverley, whose selection in midfield had raised some eyebrows prior to the match, lost the ball and Michael Carrick was slow to react. Campbell, a Costa Rican international on loan from Arsenal, nutmegged Carrick and, with Ferdinand also standing off him, curled a delightful shot into David de Gea's far post.
WATCH: Campbell digs deeper hole for Manchester United
Could the goalkeeper have done better? If so, his was the last of a series of faults that could have prevented the goal. And after that, was there a reaction from United? Not really, despite Moyes bringing on Danny Welbeck and Shinji Kagawa soon after. Robin van Persie had a super chance late on, but blasted over from nine yards out: it was the best chance of the game, and squandered. Vidic and maybe Evra are probably the only United players to emerge with credit, and it's not just the result, but also the performance, that will increase the pressure on United coach David Moyes.
The post-mortem will be a painful one; repeat this performance, though, and it could be a while before United is back in the Champions League.
Major takeaway of the day
Has Luciano Spalletti taken Zenit as far as he can? Another manager under pressure, the Italian coach has been with the club for more than three years now - longer than he spent at Roma, where he made his name as an attacking and innovative coach - and though he has won two league titles and a Russian Cup, Zenit has still never made it to the Champions League quarterfinal.
"We have a rare opportunity to not just write a chapter in our history, but to put the title on the cover story of Zenit," he told UEFA.com before the game against Dortmund.
Within five minutes, his team was 2-0 down; 10 minutes later, he subbed off winger Andrey Arshavin for holding midfielder Anatoly Tymoschuk. Zenit rallied twice but still faces a mountain to climb with a 4-2 deficit.
For all the talk of Dortmund's injury crisis - of the 11 that started last season's Champions League final, only two players (Roman Weidenfeller and Kevin Grosskreutz) have not suffered an injury this season - no one really considered Zenit's form, and with good reason. It hadn't played for 10 weeks, due to Russia's understandable winter break, but before then, had won once in eight games and Spalletti admitted he was under pressure.
"We aren't showing the sort of skill that we possess. Maybe the coach is guilty of that, in that he isn't preparing for these matches well enough," Spalletti told the Zenit website in December.
Zenit, and Spalletti, seemed to carry on where it left off before Christmas. The Italian touted himself for the vacant job at AC Milan last month and had been mentioned as a possible successor to Cesare Prandelli as Italy coach. His time at Zenit looks like it's up.
You can't say the same for Jurgen Klopp, especially after Dortmund's director of sport Michael Zorc extended his contract with the club last week. Klopp was the butt of some hilarity in the pre-match press conference when the translator employed by UEFA asked Klopp and his captain, Sebastien Kehl, which of them was the player. While both men laughed, the truth is Klopp probably could have done Kehl's job in midfield Tuesday - at least, in the first half.
How the second legs shape up
With a bit more interest, is the short answer. The first five games all ended with the teams that finished top of their group winning the away leg of their round of 16 ties - Zenit was the first home side to even score a goal, after last week's four ties were shutouts for the away sides. At least Olympiakos's well-deserved win over United offers up an intriguing second leg.
The perception that just qualifying from your group is enough has proved a false one in recent years. In the last two seasons, six of the top eight went through while in 2011, seven teams made it. So it's nothing new, but it does highlight the importance of avoiding second place in the group; and this is something Arsenal fans know all about.
Its weakened side lost at Olympiakos on Matchday Six last season and ended up drawn against eventual winners Bayern Munich in the round of 16.
Fast-forward 12 months and it was a similar story: Arsenal needed a draw on Matchday Six to finish top of Group D, ended up losing 2-0 and Borussia Dortmund took the top spot. Dortmund's reward: a game against a Zenit side that had clearly not played a competitive game for 10 weeks. As for while Arsenal, it had a reunion against Bayern, with the same outcome: a two-goal home defeat.
So while Tuesday may not have been the best for both group winners, it was a day when Arsenal fans were reminded of what might have been.