Chelsea maintained good emotional control of the first half. They played the game at a slower speed with and without the ball, didn’t have to play too aggressively to look for more goals (given the 2-0 lead from the first leg), and prevented the match from becoming very spirited, which can provide momentum for the team trailing from the first leg.
Although Porto continued to press aggressively just as they had in the first leg, Chelsea were comfortable to play the ball into and under pressure, before looking to break through it. Balls into the front three would face intense and aggressive pressure from Porto’s backline, and being able to keep the ball in these situations required quick turns, drawing fouls (pushing Porto back) and looking for switches to the wing-backs in spaces wide — which Chelsea’s frontline were more than capable of doing.
Following a forward pass, Chelsea attackers could beat their defender with the ball and set up an opportunity to move forward quickly into the final third and to create a chance against a broken defence. A foul or the ball going out for a Chelsea throw-in would push Porto back to a deeper block and give Chelsea field position to create. On the occasions where the ball was lost, Chelsea controlled the situation calmly without the game becoming broken and opening spaces up for Porto to exploit, often recovering the ball from midfield to start a dangerous attack of their own. Meanwhile, the only mistake Chelsea made at the back to give the ball away was quickly dealt with.
Without being too eager to recover the ball when defending deep, given the lead, Chelsea were much more compact to defend inside and around their box. They could keep close enough distances to the ball without risking opening up spaces on the inside or behind the backline, and when they recovered the ball from deep they often found themselves in good counter-attacking situations. A goalless first half would see Chelsea comfortably going into the second half in control of the tie.
Chelsea lost a few balls in the opening stages of the second half, but were in good positions to defend their box and slow the game down to prevent Porto from creating dangerous counters. Most of Porto’s attacks from these situations would see the ball go out of play, while the crosses that did go into the box were collected by Mendy to prevent any chances.
When Chelsea began to break through the pressure with their buildup they would again create a number of chances to score in the final third, with Porto stretched at the back. Although Chelsea missed these chances to extend their lead, they were the team that seemed more likely to score and more of the game was being played from midfield and inside Porto’s half while the clock was running down.
A number of fouls on Pulisic would again see the game becoming slow and not allowing Porto to build any momentum, while also denying Chelsea the opportunity to continue breaking through from midfield and creating chances to extend their lead. Although Porto did eventually score an excellent goal, it was too late in the game to build upon it or put Chelsea under any real pressure.
two-legged xG map for Porto - Chelsea pic.twitter.com/11LL0loAPk— Caley Graphics (@Caley_graphics) April 13, 2021
The key for Chelsea in this game, holding a 2-0 lead from the first leg, was to manage the state of the game to prevent Porto from building momentum and making it an intense and emotional game. A slower and calm game suited Chelsea to play with the ball, defend deep and maintain a clean sheet while time would run out for Porto. Porto did manage to break Chelsea’s defence late on, but only having the chance for one more long ball in the hope of a goal wasn’t enough for them to complete a comeback.