Tonight and next Tuesday, Chelsea and Porto compete over two legs for the right to face Liverpool or Real Madrid in the semi-finals of the Champions League. Last night the Spaniards took a small step closer to the last four by winning 3-1.

This is the only tie of the round forced to switch grounds through Covid travel restrictions. As a result, the rampant lion and the fire-breathing dragon will start to settle their differences not in north-west Portugal, but in another ancient walled city elsewhere on the Iberian peninsula, namely Seville.

This evening’s nominal hosts at the Ramon Sanchez Pizjuan stadium are Porto, so goals for the Blues count towards the away tally. Next week, when the pair meet again at Sevilla’s ground for the deciding leg, it is Chelsea’s turn: the first ‘home’ match to be played away from Stamford Bridge in the club’s 116-year history.

The circumstances for this last-eight clash may be unfamiliar, then, but the arena and the opponents are not. The Blues were victors at the Bombonera de Nervion (to give the stadium its other name) as recently as the group stage in December, when Sevilla were thrashed 4-0, Oli Giroud accounting for a hat-trick plus one.

Tonight’s two clubs have also met eight times previously in this competition (bringing five Blues wins, one draw and two defeats), and our shared histories are adorned with silverware-laden players and coaches. One of those, Paulo Ferreira, is a club ambassador for the Londoners.

It would seem a good time to be facing the Dragons as two of their key performers, striker Mehdi Taremi and leading scorer Sergio Oliveira, are suspended for the first leg. However, Chelsea arrive with a lot to shake off after Saturday’s shock reverse in the Premier League.

How the emotional response is channelled could go a long way to determining whether the Blues reach the last four of this competition for the first time since 2014. Porto have not been there since Jose Mourinho was in charge.

Chelsea team news

Everyone will be looking to see the response from Thomas Tuchel and his players after the unexpected plummet in standards against West Bromwich – the Blues’ largest home league defeat since 1989, and the Baggies first success in the top flight at the Bridge since 1978.

That was the first defeat under the Bavarian, but if the last two months of this season are to be successful, the recovery has to start this week. One immediate positive is the availability of experienced defender Thiago Silva. The one-match suspension for his dismissal, which helped turn the weekend game on its head, applies only to domestic fixtures. Hakim Ziyech, disappointed to be sacrificed after the red card, will at least be fresher for this fixture.

Chelsea’s defence was breached five times, but after 11 hours without conceding our head coach is unlikely to make huge changes to that area. The Londoners have won six of our past seven matches in this competition, largely through not conceding in six out of eight.

Porto have taken a defence-minded approach to some previous games in this season’s competition – they fielded five at the back in both group stage games against Manchester City – and much of Tuchel’s thinking may go into how to score the potentially vital away goal without being susceptible to counter-attacks. Options in midfield, where Albion were dominant, are improved by N’Golo Kante’s return, to the bench at least.

At the weekend Tuchel was critical of uncharacteristic soft goals conceded, but also of the lack of precision in the last 30 metres and decisiveness in front of goal. Despite the scoreline and a lethargic start, the Blues had more shots on target than Albion. Likewise, in the previous round Juventus lost despite dominating Porto with two-thirds of possession, greater accuracy in passes and crosses, and more shots on and off target.

Further forward the Blues do have the possibility to mix things up, with Tammy Abraham confirmed in the squad, Christian Pulisic training yesterday, Callum Hudson-Odoi and Kai Havertz fresh for the fray, and Mason Mount seemingly virtually certain to start after sitting out some of Saturday’s loss.

Giroud, whose involvement since late February has been restricted to the FA Cup, is the Blues’ leading marksman in this season’s Champions League with six. Timo Werner, though, has had a hand in as many goals, though three of them are assists.

The Blues will be buoyed by a record showing only Real Madrid have beaten Porto more times in continental meetings than the royal blue Londoners.

Porto to play more direct?

Porto may well lose their Primeira Liga title to Sporting but their 4-4 ousting of Juventus on away goals was the most eyebrow-raising result of the Round of 16.

Success came at a price: two key players, striker Mehdi Taremi and midfielder Sergio Oliveira, are suspended for tonight's first leg. Between them, the pair have accounted for 21 of the Dragons’ 49 goals in the Primeira Liga and nine of their 32 assists.

The Portuguese team have been coached since 2017 by Sergio Conceicao, who was in Lazio’s midfield when they lost 2-1 to Chelsea in October 2003, cup-tying him during Porto’s triumph under Jose Mourinho after he returned to the Dragons in January 2004.

Conceicao’s side finished second in a group completed by Manchester City, Olympiacos, and Marseille, collating 13 points, 10 clear of the Greek team. Unlike domestic fixtures, Porto have played relatively conservatively in this competition, conceding seven goals in the campaign (as many as favourites Bayern), and equalling Liverpool’s 14 goals for. By comparison, Chelsea have conceded two and scored 17.Against strong sides in Europe they are happy to concede possession and repel pressure, using a narrow 5-3–2 formation. After a 0-0 in the group, Pep Guardiola complained, ‘It’s difficult with eight or nine players defending in the box, defending crosses and everything.’

The positioning and reactions of goalkeeper Agustin Marchesin, 32, have often kept his side in contention.

Defensive pair Chancel Mbemba and the veteran Pepe clear their lines in no-nonsense fashion, while wing-backs Zaidu Sanusi and Wilson Manafa have been slightly more restrained in their dangerous forward raids than in domestic games.

Ahead of the defensive ranks, the Dragons’ most creative players, especially Mexico right-winger Jesus Corona and midfielder Sergio Oliveira, are expected to conjure the chances. Their usual two forwards offer different qualities: Moussa Marega pushes up onto the centre-backs’ shoulders as a combative target man, while Mehdi Taremi chases lost causes.

Taremi is one of two key men banned tonight after receiving cards against Juventus, with Luis Diaz likely to step in. The other is Oliveira, their leading scorer with five, three from the spot, and the pivot of their transitional play. Conceicao knows his talisman is hard to replace and Porto may play more directly as a result.

On-loan defender Malang Sarr, who came off the bench to keep Ronaldo and co. at bay, joined the Blues last summer but is eligible to play against his parent club under UEFA regulations.

How to watch Chelsea-Porto

This match will be covered live by BT Sport in the UK. To find the relevant broadcaster where you are, see UEFA’s TV guide.

Chelsea TV’s global available matchday shows – including early team news, exclusive interviews and analysis – are on the 5th Stand app, Facebook Live and the official YouTube channel.

Champions League regulations

Coaches are permitted to select 12 substitutes and introduce up to five in three different spells over the course of the match, plus half-time. Porto have had the benefit of this all season in the Primeira Liga.The Video Assistant Referee system is used in all games and viewing the pitch-side monitor is more prevalent than in the Premier League.

The away goals rule applies after normal time of the second leg, so when two teams are tied on aggregate the one that has scored more goals on the road advances to the next round.

Three accumulated cautions or a red card mean suspension for the next Champions League game, though all yellow cards expire at the end of these quarter-final ties.

Jorginho and Mason Mount served their ban in the previous round; a yellow card for Mateo Kovacic or Hakim Ziyech would mean them missing the second leg.

Away form an indicator?

Porto have never previously faced an English club competitively on neutral soil. As neither side in the tie has a game on their own ground, how each fares on the road in this competition becomes relevant. And it is the Londoners who lead the way going into this round, winning all four away fixtures, one more than any last-eight rival and two more than Porto, who have the worst travelling record of any remaining side.

From last eight to last four

In 16 European quarter-final ties over 55 years Chelsea have progressed to the semi-finals on 14 occasions, losing twice.

Champions League quarter-final first leg results and fixtures

TuesdayReal Madrid 3 Liverpool 1Manchester City 2 Dortmund 1

WednesdayBayern Munich v Paris Saint Germain 8pm (Munich)Porto v Chelsea 8pm (Seville)