40' Chelsea will be pleased with how they saw out that spell of Porto pressure earlier. Chilwell appeals for a free-kick after a push from Marega but nothing is given.
38' Mbemba finds Sanusi with a good ball out wide but unfortunately for Porto Sanusi is offside.
36' Porto look to recover quickly. Corona's caught offside from Pepe's throughball.
34' That's Mount's first Champions League goal with Chelsea's first shot of the game. The 22-year-old is now Chelsea's youngest-ever goalscorer in the Champions League knockout phase. Mount looks like he's been playing at this level for years.
32' Jorginho swings in a searching ball from deep and Havertz keeps it alive. It works out well for Chelsea...
31' James fires in a cross from the right and Pepe makes the clearance. Porto are almost playing with a six-man defence. It's proving hard for Chelsea to break down.
30' James finds himself out of position but recovers quickly to intercept Sanusi. The wing-back has been heavily involved for Chelsea in this opening half hour.
28' Porto go on the attack again and Chilwell has to position himself well to put a stop to Otavio's run into the box. Porto get another corner but they're penalised for a foul in the area.
26' Pepe thumps the ball forward to precisely no one. The former Madrid man is a veteran of the game and he's understandably disappointed with that. Up the other end, the offside flag goes up against Werner who tries to latch onto James' ball behind.
24' Chelsea finally manage to break upfield. Mbemba blocks Havertz' pass and now it's Chelsea's turn to test Porto from a corner. Grujic heads away James' effort and Kovacic cuts out Diaz's counter-attacking run.
23' Otavio plays a one-two with Corona, dinking the ball over the top for Corona to chase. Pepe's effort is blocked and Porto get yet another corner out of it. This time Otavio goes straight for goal, forcing Mendy to push it out. Sanusi blazes over on the follow-up.
22' The corner comes in towards Pepe but Kovacic does enough to hook it away. The ball comes off James for another Porto corner. The Portuguese champions have had a good start to this game.
20' Jorginho arrives late on Diaz and Porto have a free-kick from the left. Pepe ventures forward for it. Otavio sends it into the box and the last touch is a Chelsea one. Porto will have a corner.
18' Chelsea chase down Uribe's shot from outside the box. Chelsea have had the bulk of possession but have yet to really threaten Porto so far.
16' Mount spots James free in the penalty area and looks to loop the ball towards him from the left. Marchesin sees the pass coming and ventures out to claim it.
15' Christensen pings a direct pass forward for James. It's a pass the Dane has tried a few times already. It's unsuccessful this time but it looks like an approach which might bring Chelsea joy.
14' Porto put some silky passing together and Otavio looks for Sanusi on the overlap down the left. The Nigerian tries to volley the ball across goal but fluffs his lines and it bounces out of play.
12' Porto are starting to heat up now. Shortly after Diaz has an effort blocked, Uribe volleys just over the top left corner from outside the box.
11' Corona twists and turns to the left of the Chelsea box and hangs up a cross towards the centre. It's easy pickings for Mendy but it's Porto's first attack of note in the game.
9' Chelsea's right wing-back James has plenty of space to run into. Sanusi does well to block him off and shepherd the ball out for a goal-kick.
8' Otavio earns a free-kick for Porto down their right as Chilwell brings him down. The resulting free-kick is a strange one as Porto choose not to send the ball into Chelsea's box.
7' Chelsea take the corner short and the ball ends up straight with Porto's goalkeeper Marchesin. The away side - for the administrative purposes of this game, at least - are likely going to have to stay patient.
6' Mount goes on the run down the right channel. Sanusi gets across to intercept and puts the ball out for Chelsea's first corner of the game.
5' Porto are going to miss Oliveira and Taremi here, players who have scored plenty of goals for them this season. Chelsea continue their positive start with Mount winning a throw-in from the right.
3' Chelsea start on the front foot, making the pitch as wide as they can early on. Havertz fizzes a cross across the face of goal from the left of the box but there's no one in Chelsea colours there to make the most of it.
1' The Slovenian referee Slavko Vincic blows his whistle and Chelsea get this quarter-final tie underway!
1' d
The two teams are out on the pitch in Seville for the first of two legs on neutral territory. Porto are in their blue-and-white home kit. Chelsea are in their ember orange third kit.
This is only the second time these two teams have faced off in a Champions League knockout tie with Chelsea defeating Porto 3-2 on aggregate in the 2006-07 round of 16. Chelsea generally have a good record against Porto, winning five of their eight meetings in the competition. Will the Blues prosper again, or can Porto show the grit that helped them see off Juventus last time?
Porto boss Sergio Conceicao makes two enforced changes to the side that lost 3-2 to Juventus in the round of 16. Sergio Oliveira and Medhi Taremi are both suspended, so in come Uribe and Diaz. Their 38-year-old captain Pepe becomes the oldest outfielder to start a Champions League quarter-final game since Ryan Giggs in 2014. Thomas Tuchel keeps up his policy of rotation as he makes four changes to the Chelsea team that saw off Atletico Madrid 2-0. Christensen, Chilwell, Jorginho and Mount get the nod.
SUBS: Callum Hudson-Odoi, Emerson, Marcos Alonso, Christian Pulisic, N'Golo Kante, Kurt Zouma, Willy Caballero, Olivier Giroud, Hakim Ziyech, Tammy Abraham, Thiago Silva, Kepa Arrizabalaga.
CHELSEA (3-4-3): Edouard Mendy; Cesar Azpilicueta (c), Andreas Christensen, Antonio Rudiger; Reece James, Jorginho, Mateo Kovacic, Ben Chilwell; Mason Mount, Kai Havertz, Timo Werner.
SUBS: Toni Martinez, Romario Baro, Felipe Anderson, Mamadou Loum, Fabio Vieira, Evanilson, Francisco Conceicao, Claudio Ramos, Malang Sarr, Joao Mario, Diogo Leite, Nanu.
PORTO (4-4-2): Agustin Marchesin; Wilson Manafa, Chancel Mbemba, Pepe (c), Zaidu Sanusi; Corona, Marko Grujic, Mateus Uribe, Otavio; Moussa Marega, Luis Diaz.
Porto have reached the Champions League quarter-finals just three times since winning the competition in 2003/04, going on to be eliminated each time, while this is Chelsea's first appearance here since 2013/14. Chelsea might be considered slight favourites but with both legs set to be played in Spain, it's all to play for here in Seville.
When the draw was made a few weeks ago no doubt Porto and Chelsea will have welcomed being paired against each other. There are no easy games at this stage of the Champions League, yet this does feel like a tie of two underdogs with a semi-final against Real Madrid or Liverpool awaiting the victors.
Hello! Welcome to our live text commentary of this UEFA Champions League quarter-final first leg match between Porto and Chelsea at the Ramon Sanchez Pizjuan Stadium in Seville, Spain.
