It would be easy to assume this is almost customary when teams are as dominant as City and Liverpool have been domestically of late, but it is not strictly the case.
Their Wembley showdown will be just the third FA Cup semi-final clash of the Premier League era between teams who have begun the day in the top two of the latter competition.
Considering this is the 30th season of the Premier League, it goes to show such showdowns cannot be taken for granted.
It has been even more rare for the eventual top two in the Premier League to contest an FA Cup final, with Chelsea denying Manchester United a double in 2006-07 in the only example of that game coming to fruition.
Here, Stats Perform looks back at the two previous FA Cup semi-finals to feature the then current Premier League top two. Could City and Liverpool, packed with attacking talent, produce drama to match these thrillers?
1999: Manchester United 2-1 Arsenal (replay, after 0-0 in first game), Villa Park
Memorable moment: David Beckham scored from 30 yards, and Peter Schmeichel saved a Dennis Bergkamp penalty, but the replay in front of a smattering over 30,000 fans at Villa Park will be remembered almost exclusively for Ryan Giggs' chest hair. Sorry... goal. Yes, definitely for his goal.
Injury limited Giggs to just 24 league appearances that season, and he managed just five goal involvements across those games (3 goals, 2 assists), the fewest he would have in a Premier League campaign until 2012-13 and 2013-14, his twilight final years as a player.
After Beckham's fine first-half opener, Arsenal drew level in the 69th minute when Bergkamp scored from similarly long range with the help of a deflection, and United were in trouble when Roy Keane was sent off five minutes later. Schmeichel came to the rescue with a spot-kick save after Phil Neville tripped Ray Parlour at the death in normal time, and then it was over to Giggs. Vintage Giggs.
Early in the second half of extra time, a stray pass from Patrick Vieira was intercepted 15 yards inside United's half by Giggs in left midfield. From there he snaked through a weary Arsenal rearguard, showing remarkable close control of a bobbling ball on a pitch that was cutting up, before smashing a shot past David Seaman at his near post. Off came his shirt, Giggs celebrating wildly, United on their way to the final.
What came next: United had been a point ahead of Arsenal and third-placed Chelsea in the Premier League title race, and it remained close all the way, with victory over Tottenham on the final day making sure Alex Ferguson's side won that title. They carried off the FA Cup too, goals from Teddy Sheringham and Paul Scholes earning a 2-0 win over Newcastle United, and the most special moment came at Camp Nou, where Sheringham and Ole Gunnar Solskjaer struck late to give the Red Devils a famous 2-1 success over Bayern Munich in the Champions League final, and the first and only such treble by an English club. City might match that this season, while Liverpool could even top it, having already won the EFL Cup, with the FA Cup, Champions League and Premier League still in their sights.
2017: Chelsea 4-2 Tottenham, Wembley
Memorable moment: Nemanja Matic sealed the spoils for Chelsea with a remarkable 30-yard drive into the top corner, as the Premier League's then London elite met at Wembley.
Chelsea were four points ahead of Mauricio Pochettino's Tottenham at the top of the table, with Antonio Conte looking good to mark his first season in England with silverware. They had a double in their sights too, and although Tottenham twice came from behind to cancel out two goals from Willian in this semi-final, thanks to Harry Kane and Dele Alli, it was Chelsea who prevailed thanks to substitute Eden Hazard's sizzling low strike and a remarkable finish from Matic 10 minutes from time.
Fed a short pass by Hazard, Matic lashed an unstoppable left-footed drive into the top-right corner, thudding in off the underside of the crossbar.
What came next: Chelsea duly wrapped up the league title with two games to spare as Tottenham reluctantly settled for second, seven points off the pace in the final reckoning. But for all their domestic dominance up to that point, a savage twist arrived in the FA Cup final, where Arsenal awaited them. Arsene Wenger's Gunners finished only fifth in the Premier League, but they had kept something in reserve for Wembley as goals from Alexis Sanchez and Aaron Ramsey gave the Gunners the trophy.
Conte got his hands on the FA Cup a year later but was sacked before the new season began; after returning to football with Inter, and landing a Scudetto in Milan, Conte could not resist a return to London when Tottenham came calling last November.
