The first leg of Champions League round of 16 has finished, and it left us a few surprising results.
Ole Gunnar Solskjaer suffered his first defeat when Manchester United lost 2-0 to PSG at home, while Cristiano Ronaldo, who vows to win Champions League with Juventus, fell at his old rivals Atletico Madrid.
United have to fight back without Paul Pogba in the second leg, who was sent off in the last minutes during the defeat. Meanwhile, Anthony Martial and Jesse Lingard both got injured in that game and remain doubtful for the second leg.
Juventus, trailing 2-0 to Atletico, are also facing huge tasks as Diego Simeone's side are arguably the best defensive team in Europe. Taking the away-goal rules into consideration, their 2-goal deficit will be doubled if Atletico manage to find the net in the second leg.
However, nothing is impossible in football. Liverpool proved it, Barcelona also proved it - even in two different ways.
Now let's take a look at those greatest comebacks in the Champions League of all time. Will Manchester United and Juventus add their names to the list after the second leg?
6. Wolfsburg vs Real Madrid, 2015-16, Quarterfinal
First-leg result: Wolfsburg 2-0 Real Madrid
Second-leg result: Real Madrid 3-0 Wolfsburg
A tie which is considered as the very beginning of Real Madrid's dynasty in the Champions League. After eliminating Roma in the Round of 16, Real Madrid drew Bundesliga side Wolfsburg in the quarterfinal, a seemingly easy opponent for Zinedine Zidane's side.
However, two first-half goals stunned Ronaldo and co in the Volkswagen Arena. With a below-par performance in the defeat, Madrid's hopes once looked slim.
That was when you need a hero - Cristiano Ronaldo. The Portuguese opened the second leg with 2 goals in 3 minutes before hitting a fortunate free-kick goal into the net, finishing his unbelievable hat-trick to send Real Madrid through.
Ronaldo proved he can single-handedly overturn a 2-goal deficit. Can he do it one more time?
5. Manchester United vs Bayern Munich, 1998-99, Final
90th minute: Man Utd 0-1 Bayern
93rd minute: Man Utd 2-1 Bayern
Ronaldo isn't the only one who produced a miracle before. Ole Gunnar Solskjaer did it far earlier than him.
Manchester United were down a goal heading into stoppage time of the 1999 Champions League final. Their quest for the first treble in English history was going to fall short.
That is until Teddy Sheringham scored in the 91st minute.
But Manchester United didn't even need extra time in this one because Solskjaer's stunning goal in the final second propelled the Red Devils to their first European crown in 31 years, not to mention that historic treble.
4. AC Milan vs Deportivo la Coruna, 2003-04, Quarterfinal
First-leg result: AC Milan 4-1 Deportivo
Second-leg result: Deportivo 4-0 AC Milan
Milan's team in 2004 was loaded with the world's best stars including Kaka, Andrea Pirlo, Paolo Maldini, Cafu and Andriy Shevchenko.
A 4-1 loss in the first leg surely spelt defeat for Spanish club Deportivo La Coruna. But, as Deportivo coach Javier Irureta said before the second leg in Spain, "Miracles often happen, things you might not rationally expect."
Away from home, the defending champion and tournament favourite Milan were erratic early on, eventually succumbing to Deportivo's immense pressure in the form of an early Walter Pandiani goal.
As the Riazor crowd bellowed, a Juan Carlos Valeron header and a fierce drive from Albert Luque about a minute from halftime erased Milan's first leg lead and would send Deportivo through.
But Irureta's side wasn't satisfied yet, as they added one more for good measure on a brilliant volley from Fran to give the Galicians an astonishing quarterfinal victory.
3. Barcelona vs Roma, 2017-18, Quarterfinal
First-leg result: Barcelona 4-1 Roma
Second-leg result: Roma 3-0 Barcelona; Roma advance on away goals
Barcelona entered the second leg of their quarterfinal clash with Roma in a comfortable position.
The Catalans had not lost a match in domestic or Champions League play all season and had not tasted defeat in 18 straight matches, including a 4-1 thrashing of Roma in the first leg of the competition at Camp Nou.
But Ernesto Valverde's side came out flat-footed, allowing a sixth-minute goal to Edin Dzeko on a brilliant Daniele De Rossi long pass.
De Rossi doubled Roma's lead shortly after half-time from the penalty spot and defender Kostas Manolas finished a beautiful header past Marc-Andre ter Stegen late in the game to dramatically propel Roma to the semifinals.
2. PSG vs Barcelona, 2016-17, Round of 16
First-leg result: PSG 4-0 Barcelona
Second-leg result: Barcelona 6-1 PSG
No team had ever rebounded from a four-goal deficit in the Champions League until Barcelona shocked Paris and the world.
The first leg in France produced disastrous results for Luis Enrique's side as Paris Saint-Germain handled business, winning 4-0 behind goals from Angel Di Maria and Julian Draxler.
Coming into the second leg, Barcelona failed to secure a crucial away goal and needed to put at least five past PSG to advance to the quarterfinals. A third-minute Luis Suarez header started the scoring for Barca, who then scored two more times within the first 50 minutes to put the pressure on the French side.
PSG responded with a spectacular volley from Edinson Cavani, surely spelling doom for Barcelona. Chasing three more goals in the late stages of the game, Neymar curled a free kick past Kurzawa and just two minutes later converted a penalty to make it 5-5 on aggregate.
But Barcelona still needed another miracle to counteract PSG's away goal. In the 95th minute, Sergi Roberto incredibly struck the game-winning goal in the final seconds to complete one of the most incredible games in Champions League history.
1. Liverpool vs AC Milan, 2004-05, Final
First-half result: Liverpool 0-3 Milan
Full-time result: Liverpool 3-3 Milan
Liverpool win on penalties (3-2)
Liverpool overcame a three-goal deficit against mighty AC Milan to win the Champions League Final on penalties.
On a clear night in Istanbul, Milan quickly took the lead on a brilliant volley from captain Paolo Maldini off a cross from Andrea Pirlo.
Striker Hernan Crespo added two more goals before half-time to make it 3-0, creating a seemingly impossible task for Liverpool.
But Steven Gerrard gave Liverpool hope with a header into the right corner and Vladimir Smicer added another just two minutes later.
Milan's lead would officially be erased in the 61st minute as Xabi Alonso followed up his missed penalty by rocketing a shot into the top of the netting.
The score stayed level throughout regulation and extra time and the match headed to penalties, where Liverpool emerged 3-2 to win their fifth European Cup.