Chelsea and City will clash at Wembley for Saturday afternoon’s 145th FA Cup final in what should be an incredible game between two sides in very different form.
City are now unbeaten in each of their previous nine matches in all competitions whilst Chelsea drew 1-1 at Anfield against Liverpool to end their 6 games losing streak.
Pep Guardiola's side faced Crystal Palace earlier this week and travel to Bournemouth after the Chelsea clash in what is a very busy spell for the side.
Speaking to BetVictor, Gallas believes this hectic schedule could be used to Chelsea’s advantage as they face one of their toughest tests of the season.
"If Manchester City play against Chelsea the same way they did against Arsenal in the Carabao Cup final, it will be very hard for Chelsea in the FA Cup final.
"Even though Chelsea drew 1-1 with Liverpool, they still don't have the confidence and are suffering. Obviously, anything can happen in one game, but I think it will be hard for Chelsea.
"If Chelsea do win the game, I think it will be because the Manchester City team are tired from the amount of fixtures recently. They could be tired from the Crystal Palace game and that could give Chelsea the chance to win."
City are expected to do a cup double this season, but Chelsea could pull off a shock result on Saturday afternoon as they aim to use fatigue to their advantage.