Two of the most in-form sides in the Premier League, Manchester City and Chelsea, are set to face off at the Etihad Stadium in what could be a fixture of massive importance to the Cityzens. A win against the Blues would see Pep Guardiola's City be crowned Premier League champions for the third time in four seasons to cap off what has been a thoroughly dominant campaign in the top-flight.Manchester City and Chelsea have had two very contrasting meetings so far this season. Guardiola's side demolished them at Stamford Bridge in one of Frank Lampard's final games as Blues boss, winning 3-1 on the night.The second meeting came at Wembley more recently in the semi-finals of the FA Cup, where Thomas Tuchel set up Chelsea for a masterful display against his Catalan counterpart to win 1-0.MAN CITY VS. CHELSEA THE CHAMPIONS LEAGUE FINAL IS SET 🍿 pic.twitter.com/0CwFhpFVHp— B/R Football (@brfootball) May 5, 2021Apart from the fact that this could be a title-clinching game for Manchester City, another interesting dynamic is that the two sides are set to play each other once again in three weeks time in the UEFA Champions League final. The Cityzens thrashed Paris Saint-Germain while Chelsea brushed aside Real Madrid to get to the showcase event in Istanbul.With the stage set up for Manchester City's potential coronation at their own stadium against Chelsea, here, we take a look at five key battles that could define the outcome of the game.Key Battles between Manchester City and ChelseaJoao Cancelo v Ben ChilwellManchester City v Chelsea: Emirates FA Cup Semi FinalWhen the two sides last met at Wembley, one of the key features of Chelsea's approach was to pin back Manchester City's marauding wide defenders, stifling their threat from wide areas. This forced City to play more centrally, where Chelsea were more than ready to handle their threat. On Saturday, Ben Chilwell — who had an excellent outing against Joao Cancelo last time out — will be key once again.The Englishman was one of Chelsea's biggest threats down the left-hand side and, impressively, managed to support his attackers while containing Cancelo's threat remarkably well. The 24-year-old is in sublime form and will be key in helping Chelsea keep Cancelo quiet during the game.Riyad Mahrez v Antonio RudigerFC Porto v Chelsea FC - UEFA Champions League Quarter Final 3: Leg OneAnother massive duel that could define the game is one between Riyad Mahrez and Antonio Rudiger. The German defender has benefitted hugely from Thomas Tuchel's arrival at the club. Playing on the left of the defence, he will need to be at his sharpest to deal with Mahrez. If Cancelo keeps Chilwell occupied, Mahrez could find more space to operate in between the centre-back and wing-back.The Algerian forward has been in blazing form in 2021 and was the star of their UCL semi-final against PSG, scoring thrice in two games. Playing off the right-hand side, Mahrez will be one of City's biggest threats on the night.Riyad Mahrez’s game by numbers vs. PSG: 81 touches 10 duels won 8 touches in opp. box 6 ball recoveries 5 take-ons 4 crosses 4 shots 3 shots on target 3 interceptions 2 chances created 2 goals Fantastic again. 👏 #UCL pic.twitter.com/aF5JDeJ66i— Squawka Football (@Squawka) May 4, 2021Rudiger has a knack for making regular forward runs, due to which he could possibly leave behind plenty of space for Mahrez to exploit. The City star has shown that he can wreak havoc if allowed time and space to cut in onto his left.Also read: 5 Players who have created the most chances in Europe this season (2020/21)