Pep Guardiola named a remarkably strong side to face Peterborough United at the Weston Homes Stadium on Tuesday evening, with Phil Foden, Jack Grealish, Gabriel Jesus and Riyad Mahrez also starting against Grant McCann's troubled team.Despite the personnel, it took the Blues until the 61st minute to break the deadlock, Anthony Munoz Jersey as the Cambridgeshire club put up fierce resistance, and almost took the lead in the first-half through Jeando Fuchs' effort, which was well saved by Ederson at his near post.Eventually, Manchester City would take Bobby Hart Jersey the lead through Riyad Mahrez, as the Algerian smartly finished, as he rolled the ball into the far corner.Jack Grealish would guarantee Manchester City's place in the FA Cup quarter-finals for a third succe sive season seven minutes later, as the 100 million man scored his ever FA Cup goal.The win, which was the Blues' 30th victory of the campaign, may however be bittersweet, after Pep Guardiola revealed the worrying reason for replacing both his centre-backs at half-time.Scroll Renell Wren Jersey to ContinueJohn Stones and Aymeric Laporte came on for Nathan Ake and Ruben Dias at the start of the second-half, and Pep Guardiola said post-match that the changes were enforced due to ' .'Ake, who was making his 14th start of the season, was taken off after 45 minutes due to a ' ' according to Pep Sam Hubbard Jersey Guardiola, with the Dutchman having taken a heavy fall midway through the first-half.Dias was also substituted at half-time, with the Catalan revealing post-match, that the Portuguese defender was' .'Manchester City are set to welcome rivals Manchester Auden Tate Jersey United to the Etihad Stadium on Sunday in the Premier League, with the Blues looking to extend their lead over Liverpool, at the top of the table.You can follow us for live updates here: