Chelsea, Liverpool and Manchester City all secured their places in the knockout stages of the Champions League but there's work to do for Manchester United. Find out who enhanced their reputation for the Premier League clubs as we round up the hits and misses from the Champions League...
How do you tell a man who scores four goals in a Champions League away game at Sevilla - a side where only one English team has ever won before - that it's not enough to keep his place?
If Olivier Giroud doesn't start against Leeds United for Chelsea on Saturday night, that's exactly what Frank Lampard will have to do.
And with international manager Didier Deschamps already pushing him to 'find a solution' to his lack of game time, you would forgive him if it proved the final straw against yet more months sat on the bench at Stamford Bridge.
Lampard admitted Giroud - the first Chelsea player to score four in one game since Lampard a decade ago - has a chance of a first league start since the final day of last season on the back of his haul.
He told BT Sport after the match: "When you play Oli and utilise his strengths, and still maintain threats from the sides, the speed of getting in behind or quality of play through the middle, you see a real nice balance about our attacking play."
What reason is there to drop him? Tammy Abraham, who missed two gilt-edged chances against Tottenham last weekend, is hardly in sparkling form in the Premier League with two in his last seven. Pace? Timo Werner provides plenty.
Sevilla may have changed eight of their first-choice starting line-up but this was no flash-in-the-pan from Giroud. He's a World Cup-winner. He has more Champions League goals than Zinedine Zidane. He has been there, done it, got the t-shirt. And all on the back of 47 minutes of Premier League football this season. It was a world-class forward display.
It might not make a tangible difference to Chelsea's season whether Giroud plays on Saturday or not. But then again, Chelsea owe all of their last five Champions League strikes - two of them winners - to the 34-year-old, as well as goals which would have cost them eight points, and a top-four place itself, from last season. So losing him is likely not in Lampard's best interests.
Sat Dec 5: Leeds (h) - live on Sky Sports
Tues Dec 8: FK Krasnodar (h)
Sat Dec 12: Everton (a)
Tues Dec 15: Wolves (a)
Mon Dec 21: West Ham (h)
Sat Dec 26: Arsenal (a) - live on Sky Sports
The knives are out again for Antony Martial. Can he be relied upon to score consistently when it matters most? There isn't really a middle ground with the Frenchman; he's either hot or cold.
Against PSG, he froze.
His moment came on 49 minutes when after some sublime chemistry between Marcus Rashford and Edinson Cavani on the right flank, Martial had the chance to finish off what would have been a classic Manchester United goal in Europe.
Instead, he leaned back like a player with zero confidence and skied a chance that all strikers in the Champions League should be finishing in their sleep. It was one of three opportunities he had on the night where he wastefulness leaves United with a job to do in Leipzig next Tuesday.
After an impressive 2019/20, where the Frenchman scored 23 goals in all competitions, Martial is struggling for form at Old Trafford this season, which is again leaving fans divided on his worth for the club. He's yet to score in 379 minutes of Premier League football with his most eye-catching contribution being the red card against Tottenham.
For those still undecided, it was a night to understand why Giroud starts ahead of Martial for France.
And now, Martial's starting berth at Manchester United could also be under threat.
Sat Dec 5: West Ham (a) - live on Sky Sports
Tues Dec 8: RB Leipzig (a)
Sat Dec 12: Man City (h) - live on Sky Sports
Thur Dec 17: Sheffield United (a)
Sun Dec 20: Leeds (h) - live on Sky Sports
Jurgen Klopp's Liverpool squad is being tested to its limits right now but the performances of three youngsters in the 1-0 win over Ajax on Tuesday evening will have delighted the manager.
Neco Williams provided the assist for Curtis Jones to capitalise on Ajax goalkeeper Victor Onana's error and finish neatly at the far post for the only goal of the game. At the other end of the pitch, young goalkeeper Caoimhin Kelleher was impeccable deputising for the injured Alisson.
This felt like an important performance from Williams given the fact that he was substituted at half-time against Brighton on Saturday. The subsequent hamstring injury to James Milner, who Klopp had preferred to switch to right-back rather than allow the young Welshman to continue, means that the onus will now be on him to fill the void left by Trent Alexander-Arnold. He responded in style.
Thanks to the efforts of Kelleher, Williams could also celebrate his role in a clean sheet. It would have been easy for Klopp to turn to the far more experienced Adrian but his faith in the 22-year-old Irishman was emphatically justified. Kelleher produced one full-stretch stop in the first half but it was his save to keep out Klaas-Jan Huntelaar's header from point-blank range that secured the victory that ensures Liverpool have qualified as the winners of Group D with a game to spare.
That will take the pressure off in Denmark next week and allow Klopp to put the focus back on the team's Premier League campaign. Liverpool can now do so in the belief that for all the injury problems, this is a squad that is a little bit deeper than many had thought.
Even so, while Klopp will have been heartened by the victory, and feeling more confident about the capabilities of the deputies, this was still an evening in which we discovered that Liverpool could be without Alisson for the visit of Wolves at the weekend.
The Brazilian goalkeeper has been a huge figure in Liverpool's success since the moment he arrived and if Klopp is without his first-choice goalkeeper on Sunday he will need his team to improve on their record in the competition without him so far this season - that 7-2 defeat to Aston Villa and the 2-2 draw with Everton.
At least Andrew Robertson continues to battle through. The left-back went down with a heavy knock during the first half against Ajax and it looked as if Liverpool would be contesting the rest of the game without their entire first-choice back four as well as their goalkeeper.
That Robertson not only continued but shone during the second half is testament to his appetite for the fight. Liverpool are going to need him - and that spirit - if they are to press on through this difficult period.
Sat Dec 5: Wolves (h)
Wed Dec 9: Midtjylland (a)
Sun Dec 13: Fulham (a) - live on Sky Sports
Wed Dec 16: Tottenham (h)
Sat Dec 19: Crystal Palace (a)
Sun Dec 27: West Brom (h) - live on Sky Sports
Since Vincent Kompany left Man City 18 months ago, you could rarely claim that Pep Guardiola's side were defensively solid, or at least consistently. However, the transformation of Man City's backline is finally paying dividends, especially in Europe.
Man City have kept four consecutive clean sheets in the Champions League for the first time, as many as they managed in the group stages in their last two campaigns combined - a truly incredible turnaround.
City restricted Porto to just two shots, 31.9 per cent possession and the hosts had no corners, although it was clear that the hosts had set up to defend against a Man City side who often see the majority of the ball. Ruben Dias continues to impress at the back after his summer arrival with Eric Garcia and Oleksander Zinchenko also given their chance to stake a claim.
But turn a brief eye to the bench, and you had the likes of Aymeric Laporte, Kyle Walker, Benjamin Mendy and Nathan Ake all waiting in the wings. They were joined by John Stones, who should be commended on his recent turnaround in form.
Going forward will be more of a concern. It's the first time they have had a goalless draw in the Champions League group stages, but did have 18 shots. Credit for that must also go to man of the match Agustin Marchesin, but Guardiola's sides have never been goal-shy.
Ultimately, Man City needed a point to ensure they finish as group leaders, and that's exactly what they did. With that job done for now, they must now bring more of that defensive solidity into the Premier League, especially against local rivals Manchester United on Saturday December 12, live on Sky Sports.
Live Premier League
Sat Dec 5: Fulham (h)
Wed Dec 9: Marseille (h)
Sat Dec 12: Man Utd (a) - live on Sky Sports
Tues Dec 15: West Brom (h)
Sat Dec 19: Southampton (a)
Tues Dec 22: Arsenal (a) - live on Sky Sports