City have the chance to move four points clear at the top of the Premier League with a victory in the game at the Etihad Stadium at 15:00 (UK) on Saturday.
Meanwhile, Leeds are fighting for their Premier League survival, sitting just above the drop zone on goal difference.
The Yorkshire Club changed their coach in the build-up to the game, replacing Javi Gracia with the vastly-experienced Allardyce and Guardiola believes his side will need to be flexible in their approach to the game.
“Always a new manager has an impact on the players in the first one or two games and of course they, and all teams, are playing every game for important things,” the boss said. “Leeds [are playing] to stay here and the impact is huge.
“I don’t know what system they are going to play, we don’t have any info so we have to adapt quickly after 10-15 minutes because we can’t imagine what he is going to try to do.
“Again it’s a massively important game for us.”
The Leeds clash is the latest of a run of important fixtures as we battle for trophies on three fronts, with our Champions League semi-final first leg away to Real Madrid three days later.
With City also reaching the FA Cup final and a Wembley date with Manchester United following the climax of the Premier League season, Guardiola is happy with how his squad have coped with the challenge so far.
“We played many, many games during the season so we are used to it,” he added.
“It’s not new. What we have done, being here until the end, we have done in the past – it’s no surprise. I admire my players that again and again they have done it.”
