Editor's Note: This story was published in December but has been updated to reflect Manchester United's change in manager, Neymar's foot injury, as well as other key developments since the draw was made.
The path to the 2019 Champions League final in Madrid has become clear following the draw for the round of 16, which has thrown together some of Europe's biggest clubs.
Heavyweight clashes between Liverpool and Bayern Munich, Manchester United and Paris Saint-Germain, Atletico Madrid and Juventus, and Ajax and Real Madrid ensure that some of the most successful clubs in the game will be facing elimination at the first knockout stage.
The draw has been kinder to leading contenders such as Manchester City and Barcelona, but who will come out on top when the Champions League resumes?
SCHALKE vs. MANCHESTER CITY
It might lack glamour, but Manchester City's pairing with Schalke is a dream draw for the Premier League champions.
Schalke, who qualified as runners-up behind Porto in Group D, are languishing in the bottom half of the Bundesliga, having won just six league games all season. Coach Domenico Tedesco has a squad low on the quality needed to worry City, so this tie should be a formality for Pep Guardiola's team.
Leroy Sane will return to Germany to face his former club, and it really should be a happy homecoming for the City winger in what is likely to be a mismatch. As for omens, City's only European title -- the 1970 Cup Winners' Cup -- came after beating Schalke en route to the final.
Who will go through? Manchester City
ATLETICO MADRID vs. JUVENTUS
Arguably the tie of the round sees two of the Champions League's unluckiest clubs collide. Atletico and Juventus have each reached, and lost, two finals during the past decade and both have pushed the boat out financially to ensure that 2019 is their year.
Atletico, who host the final at their own Wanda Metropolitano Stadium, brought in Diego Costa, though he has suffered from poor form and injury, as well as Thomas Lemar and Alvaro Morata. They also retained the services of Antoine Griezmann and Diego Godin. Juventus gambled heavily on Cristiano Ronaldo and also brough Leonardo Bonucci back to the club after a year in Milan.
This tie is very close to call. Both possess outstanding defences, terrific work rate and quality forwards, but Atletico's determination to play in their own final might just swing things in their favour.
Who will go through? Atletico Madrid
MANCHESTER UNITED vs. PARIS SAINT-GERMAIN
When the draw was made in mid-December, this tie threatened to be the biggest mismatch of the round, with Manchester United in crisis and PSG cruising at the top of Ligue 1, having won their qualification group ahead of Liverpool and Napoli.
But within 24 hours of the pairing being made, Jose Mourinho was sacked by United, whose subsequent revival under caretaker manager Ole Gunnar Solskjaer has given them real hope of success against the French champions. Marcus Rashford and Anthony Martial have been two of the big beneficiaries.
PSG, meanwhile, have been beset with problems. Neymar will miss both legs because of injury, as might Edinson Cavani, Adrien Rabiot continues to be overlooked because of a contract dispute and there are fitness concerns over Marco Verratti. A 2-1 Ligue 1 defeat at Lyon on Feb. 3 also dented confidence.
Who will go through? Manchester United
TOTTENHAM vs. BORUSSIA DORTMUND
Tottenham made it into the knockout stages only after a final-day draw against Barcelona in the Camp Nou earned second spot in Group B for Mauricio Pochettino's team and the subsequent pairing with Dortmund, who they beat twice in last season's group stage, looked give them a route to the quarterfinals.
Despite Lucien Favre's team topping the Bundesliga, the Premier League side appeared to have the edge, but injuries to Harry Kane and Dele Alli will rule the England pair out of the first leg and could also see them miss the return game in Germany. Dortmund, meanwhile, boast attacking quality that includes Jadon Sancho.
This tie is now a tough one to call, but although Spurs appear slight favourites on current form, will it be enough?
Who will go through? Tottenham
LYON vs. BARCELONA
Barcelona still regard last season's Champions League as a missed opportunity after being humiliated by Roma in the quarterfinals, crashing out after a 3-0 defeat in the Stadio Olimpico. But their mission to make amends by winning this season's competition in Madrid has been boosted by the pairing with Lyon, who will see qualification for this stage as success in itself.
Lyon beat Manchester City at the Etihad Stadium and drew with the English champions in France during the group stage, but they will be heavy underdogs against Lionel Messi & Co.
Barcelona's biggest danger will not be the unpredictable talents of Lyon's Memphis Depay; it will be the threat of complacency. But after the defeat in Rome last season, don't expect them to fall short again.
Who will go through? Barcelona
AJAX vs. REAL MADRID
A real clash of European heavyweights, with the reigning champions Real coming up against Erik ten Hag's resurgent Ajax team.
Ajax emerged as runners-up behind Bayern Munich in Group E and did so with an unbeaten record, despite the inexperience of their team. Matthijs de Ligt (19) and Frenkie de Jong (21) are the young stars driving Ajax back to prominence, with the experienced Dusan Tadic netting eight goals in 12 European games this season.
Real, meanwhile, have been poor in defence of their trophy, with managerial upheaval and the sale of Cristiano Ronaldo hitting them hard. They qualified as group winners, despite losing twice to CSKA Moscow, and should have the pedigree to beat this young Ajax team, but don't rule out the Dutch outfit.
Who will go through? Real Madrid
LIVERPOOL vs. BAYERN MUNICH
A tie worthy of the final, with both clubs possessing the pedigree to target success in Madrid.
Bayern have been inconsistent under Niko Kovac, however, with the perennial German champions five points adrift of leaders Borussia Dortmund in the Bundesliga. They will be without Thomas Muller for the first leg at Anfield following his red card against Ajax, although Liverpool will also miss the suspended Virgil van Dijk in that game.
Liverpool top of the Premier League and will be favourites on current form, with former Dortmund coach Jurgen Klopp relishing a return to Germany. But it is a tough draw for both teams and the pendulum could swing back toward Bayern, who are unlikely to be fazed by the Anfield atmosphere in the first leg.
Who will go through? Bayern Munich
ROMA vs. PORTO
Roma are struggling in sixth position in Serie A, but have great experience throughout their squad and memories of last season's run to the last four should make them slight favourites in this tie.
Porto are difficult to gauge, having qualified as winners of the weakest group ahead of Schalke, Galatasaray and Lokomotiv Moscow, but they top their domestic league and are still unbeaten in Europe this season. In Moussa Marega, they have a forward in Champions League form, with five goals in six games.
Who will go through? Roma