This was a first meeting between the two sides and City came into it needing a morale-boosting victory after falling off the pace in the Premier League. They got precisely that with an unforgettable scoreline.
Antoine Semenyo's signing adds a different dimension to City's attack and he showed the versatility that he will add to the frontline by starting on the left. He had a quiet first half, but came to life in the second with a goal to follow-up his assist.
Despite the early scare through Liam Oakes, City ran riot in the contest – defender Max Alleyne netted his first goal on only his second appearance, while Rodri added a tremendous, long-range strike to settle any nerves and put City in total command.
Exeter were panicking every time the ball came into their box and captain Jake Doyle-Hayes saw the ball bounce off him and into the net, while Jack Fitzwater inadvertently put through his own net from Tijani Reijnders' low cross.
Winger Ryan McAidoo, who was also given a debut on the opposite flank to Semenyo, also impressed with an eye-catching performance from the right-hand side.
The 18-year-old, signed from Chelsea's academy two years ago, gave Exeter left-back Oakes a torrid afternoon with his tricky and darting runs – he scored the goal his showing deserved with a confident finish into the bottom corner late on.
Lewis' double and Reijnders' beautiful finish made it 16 straight home victories for City in this competitions, a run dating back a decade.
Exeter boss Gary Caldwell was part of the Wigan Athletic squad who stunned City in the 2013 FA Cup final and his current crop may have had thoughts of delivering another shock FA Cup story had Oakes converted early on.
Birch smashed in superbly in front of his own fans in the 90th minute, but the visitors were thoroughly thrashed and totally outclassed and they have now been beaten in their past 11 FA Cup ties against top-flight sides.
