Real Madrid seek first Chelsea victory, Guardiola's semis record - Champions League in Opta numbers
Two former Champions League winners do battle in Madrid while aspiring first-time champions PSG and Manchester City meet in Paris.
It is business time in the Champions League as the 2020-21 semi-finals get under way with the first legs this week.
Chelsea visit Real Madrid, who have seen pre-match questions focus on their continued pursuit of the controversial European Super League.
In the other tie, Paris Saint-Germain are the only remaining outfit not to have signed up for the competition prior to its collapse, gaining favour with UEFA.
They have a tough ask against Manchester City, however, after Pep Guardiola's men collected their first piece of silverware this season in the EFL Cup final.
Using Opta data, we break down the two matches...
Real Madrid v Chelsea: Los Blancos yet to beat Blues or Tuchel
When English football fans consider their country's most-consistent representatives in the Champions League, Chelsea will not be the team that immediately springs to mind for most.
Yet this will be the Blues' eighth semi-final appearance at this stage of the competition, a record among Premier League sides, and they have every reason to feel positive about the Blues' chances here.
They have only lost the first leg in one of their previous seven Champions League semis and head into the tie in good shape domestically, with Thomas Tuchel inspiring a significant improvement in their fortunes since taking over in January.
The German was in charge of PSG as they lost in last season's final to Bayern Munich but boasts a strong record against Madrid, having faced them more often without losing in this competition than any other side (W1 D3). The only other coach to take them on as many times in the Champions League and not lose is Gerard Houllier (P4 W2 D2).
Further to that, Madrid's record against Chelsea is poor, as they've not won any of their three previous meetings. Los Blancos haven't faced any other side more often without winning in their entire history.
A key factor in Chelsea's run to the semis has been their solidity at the back, and Edouard Mendy has more than played his part.
The Frenchman has let in just two goals in his first nine Champions League matches; if he keeps a clean sheet on Tuesday, he will match the record set by ex-Madrid man Keylor Navas for fewest conceded in a goalkeeper's first 10 games.
Paris Saint-Germain v Manchester City: Pep back in the big time
If Madrid and Chelsea are vastly experienced at this level, the same is not exactly true of PSG and City. The Ligue 1 club are playing their third Champions League semi-final, while this is City's second.
Indeed, City have only progressed through one of their prior three semis in all European competitions, winning the Cup Winners' Cup on that occasion in 1970.
PSG are finally getting to grips with UEFA's premier club tournament, however, becoming only the third French team to reach the last four in consecutive seasons - after Saint-Etienne 1975-76 and Marseille 1990-91 in the European Cup - and bidding to be the ninth side to play back-to-back finals.
They will require a first win over City to get there, though, drawing two and losing the other of their previous three meetings. Only against Juventus (eight), Arsenal and Milan (both four) have PSG played more games without winning in their history.
And Guardiola, having finally returned to this stage, has the know-how his players might lack. This a record-equalling eighth Champions League semis appearance, level with Jose Mourinho.
Mauricio Pochettino, then Tottenham manager, eliminated Guardiola in their only past European clash two seasons ago at the quarter-final stage, although the Catalan coach has 10 career wins against the PSG boss.
Pochettino will rely heavily on Neymar, who has either scored (three) or assisted (one) in each of his previous three Champions League last-four outings, while Guardiola can turn to Kevin De Bruyne, with four goals and four assists across his past seven knockout appearances.
De Bruyne scored in both legs when City beat PSG in the 2015-16 quarter-finals and could join Neymar (four), Lionel Messi and Marcus Rashford (both three) in netting against the Parisians in three consecutive Champions League games.