English clubs return to European action this week with the start of the 2020-21 Champions League group stage.
Chelsea host Sevilla and Manchester United travel to Paris St Germain on Tuesday, while Manchester City face Porto and Liverpool play away to Ajax the following evening.
Here, the PA news agency takes a closer look at the opposition clubs.
Coaches
Sevilla: Former Spain and Real Madrid head coach Julen Lopetegui has been in charge at the Ramon Sanchez Pizjuan since June 2019.
PSG: German coach Thomas Tuchel has won successive Ligue 1 titles since replacing Unai Emery at the Parc des Princes in 2018.
Porto: The Dragons are managed by ex-Portugal winger Sergio Conceicao. The 45-year-old had two spells with the club as a player and returned as coach in June 2017.
Ajax: Two seasons ago, Erik Ten Hag led Ajax to the semi-finals of the Champions League for the first time since 1997, having succeeded the sacked Marcel Keizer in December 2017.
European pedigree
Sevilla: The Spanish side have limited Champions League pedigree but are the reigning Europa League holders, a competition they have won a record six times.
PSG: Having previously failed to go beyond the quarter-finals, big-spending PSG reached last season's final, losing 1-0 to Bayern Munich in August.
Porto: Jose Mourinho guided the Portuguese side to a shock triumph in 2004. Monaco were beaten 3-0 by Mourinho's men in the final in Gelsenkirchen.
Ajax: The Amsterdam club are four-time winners of the competition, most recently in 1995 under Louis Van Gaal. They have also been runners-up twice.
Form
Sevilla: Los Rojiblancos suffered a 1-0 defeat at Andalusian rivals Granada on Saturday, their first LaLiga loss from four fixtures this season.
PSG: French champions PSG sit second in Ligue 1 on the back of five successive wins, including scoring 10 goals in their past two games. The fine form followed consecutive defeats.
Porto: The 29-time and reigning Portuguese champions have gone two games without victory. Saturday's 2-2 draw with Sporting Lisbon followed a 3-2 home loss to Maritimo.
Ajax: Ten Hag's men have taken 12 points from a possible 15. They recovered from a 1-0 loss to Groningen to thrash Heerenveen 5-1 on Sunday.
Previous meetings
Sevilla: Tuesday's Stamford Bridge clash will be Chelsea's maiden match against the Spaniards.
PSG: Marcus Rashford's controversial late penalty sent Manchester United through to the competition's quarter-finals on away goals in 2019 on their only previous meeting with PSG. The two-legged tie finished 3-3 on aggregate.
Porto: City, under the management of Roberto Mancini, defeated Porto 6-1 on aggregate during the last 32 of the 2011-12 Europa League. Sergio Aguero scored in each leg.
Ajax: Liverpool were beaten 5-1 on their only previous trip to Ajax, part of a 7-3 aggregate loss in the second round of the 1966-67 European Cup.
