Thomas Tuchel's Chelsea put their shocking defeat to West Brom with a sensational win away to Porto.
The game was brought to life when Jorginho found Mason Mount who netted for the Blues and give them that crucial away goal.
In the second half, Porto were desperate to level but had no answer for Chelsea's ruthless backline.
Late on in the second half, Ben Chilwell doubled Chelsea's lead to give them a two-goal lead going into the second leg.
Here's our five things we learned:
1) Mason Mount the hero again
In a game where Chelsea needed a hero and a game-changer, Mason Mount was that player. The Blues were not at their best in the first half but the game changed late on in the first half. Jorginho's pass found Mason Mount who slotted the ball past the keeper. The young Englishman has been instrumental throughout the season. That moment from Mason Mount put Tuchel's side in the driving seat.
2) Reece James deserves the plaudits
The rise of Reece James continues. The young wingback put in yet another top-class display. With the issue as to who will be England's first choice wingback for the Euros, James is continuing to show why he deserves to be one of the first names on the teamsheet. In the game with Porto, James covered the ground well and was always providing cover for his fellow teammates. Even when Chelsea were on the back foot, James was always first to react and get Chelsea back on the ball.
3) Mateo Kovacic a maestro in midfield
With N'Golo Kante not fit enough to start, the onus was on Mateo Kovacic to put a quality shift in. Throughout the game, Porto piled the pressure on Chelsea with their high-press. However, when Mateo Kovacic was on the ball, despite a shaky start, the Blues managed to get back on top due to the Croatian's sheer calmness with possession. Kovacic was also a catalyst in driving the ball forward and providing opportunities for his fellow teammates.
4) The perfect response following the Blues' defeat to West Brom
Going into the game with Porto, the pressure was all on Chelsea to react and get the win in Seville. Thomas Tuchel got his side spot on against the Portuguese giants. As well as that, Tuchel's substitutions also deserve some credit as he made them at the right time in the game. Even though it wasn't vintage Chelsea, they did enough to beat Porto's press and take control of the tie. The side will be raring to go in the second leg following those two vital away goals.
5) Chelsea have those vital away goals
In the Champions League, it is essential that a team gets an away goal in the first leg. This is down to the fact that it gives them an opportunity to pounce in the home leg. What was impressive about Chelsea's performance against Porto, the Blues were defensively solid and managed to keep the Portuguese side at bay and frustrate them. On top of that, the Blues went on to add to their lead. This now puts the pressure on the Portuguese side in the second leg.
Next up for Thomas Tuchel's side is Crystal Palace in the Premier League.