The cross from the right was curling away from goal at shoulder height when Mehdi Taremi took off, connecting with a spectacular scissor kick that sent the ball into the top corner from 12 meters out.
A beautiful goal — arguably the best in the Champions League this season — to settle an ugly match.
It wasn't enough for Porto.
Chelsea qualified for the semifinals for the first time since 2014 despite a 1-0 loss to the Portuguese champions on Tuesday, the English team going through 2-1 on aggregate to meet either Real Madrid or Liverpool for a place in the final.
Aside from Taremi's stunning, acrobatic effort in the fourth minute of second-half stoppage time, Chelsea successfully stifled Porto in what proved to be something of an arm-wrestle and was happy to rely on the away goals scored by Mason Mount and Ben Chilwell in the first leg, which was also played in Seville because of coronavirus restrictions.
It wasn't pretty but Chelsea manager Thomas Tuchel didn't care.
“I can imagine that both games were not the nicest games to watch on the television for spectators who look for entertainment,” Tuchel said. "I can totally accept that, but it's very hard to play your best game against Porto.
“Part of a performance is not letting your opponent perform. This is what they do and this is what we do also. Today was the day to hang in.”
The niggly nature of the quarterfinal extended to the sidelines, with Tuchel and Sérgio Conceição exchanging words at the final whistle and the Porto coach showing his frustration by cutting short his post-match news conference after questions about the confrontation.
Tuchel shrugged it off. He has bigger concerns, firstly an FA Cup semifinal match against Manchester City on Saturday and then a second straight Champions League semifinal on a personal basis. Last year, he was at this stage with Paris Saint-Germain and advanced to the final, where his team lost to Bayern Munich.
PSG avenged that loss by knocking out Bayern on Tuesday, progressing on away goals after losing the second leg 1-0.
Tuchel doesn't have the star quality of PSG at his disposal at Chelsea, just a young, hard-working squad which is outperforming expectations — albeit despite a spending spree of around $300 million in the last offseason.
“We take it like an adventure,” he said. "It’s a big step to be in a semifinal for them. This is a very, very big achievement.
“You see the last time Chelsea has been in a semifinal, so we are not used to being there ... We need every minute to learn, to grow. You cannot improve without these experiences.”
Under Tuchel, who replaced the fired Frank Lampard in January, Chelsea has only conceded one goal in four knockout matches, having nullified Atlético Madrid in the last 16. While he has largely sorted out the team’s defense, Chelsea’s attack is still a work in progress and will likely need to improve if it is to win the competition for a second time, after 2012.
A virtually chanceless second leg often got bogged down in midfield, where N’Golo Kante shone for Chelsea on his return from a hamstring injury. Chelsea relied on counterattacks through the lively Christian Pulisic and Mount but ultimately was as unthreatening as Porto.
Porto, for its part, tried to lean on its strength at set pieces and crosses into the penalty area to find a way back into the quarterfinal and they were the only times Chelsea looked perturbed, with a header from Taremi — a 63rd-minute substitute — from one wide delivery easily saved by goalkeeper Edouard Mendy.
He made a much cleaner connection with his outrageous volley in injury time, the ball flying into the top right-hand corner and leaving Mendy motionless.
There was no time for Porto to find a second goal, though.
“I would risk to say that was one of the best matches the club has played on a technical basis in the Champions League,” Conceição said.
“We were superior in both matches but we lacked a bit of efficiency against these types of teams.”
It's Chelsea going through, though, with Madrid its likely opponent. The Spanish team leads Liverpool 3-1 after the first leg.