After two successive fifth-placed finishes, Brendan Rodgers’ FA Cup winners have lacked their usual spark this term, winning just six of their 16 Premier League matches.
By contrast, City have won their last eight in the competition to open up a three-point lead at the top of the table.
That should make the champions firm favourites for the Boxing Day clash between the two sides but Guardiola does not necessarily see it that way.
“Leicester remain Leicester,” said Guardiola, whose side beat the Foxes 1-0 at the King Power Stadium in September.
“For me, they remain (with a) top-quality manager, absolutely, with exceptional players in all departments.
“But sometimes, in seasons, there are periods of highs and lows. Maybe we are used to seeing Leicester up there all the time.
“Hats off to how well this club works in many senses – recruitment of players, adapting and adjusting to many situations – but sometimes there are periods that they are not consistent all the time.
“It happens but from one game to one game, when you see the quality they have, everything can happen. I give the same value to them and the same credit because, when you see quality they have, starting from the keeper and finishing with (Jamie) Vardy, they are exceptional.”
The match will be Leicester’s first league outing since thrashing Newcastle 4-0 on December 12 after fixtures against Tottenham and Everton were postponed.
They returned to action in the Carabao Cup in midweek but were beaten on penalties in their quarter-final tie by Liverpool.
City have had a rare midweek break this week but have scored 11 goals without conceding any in their last two matches against Leeds and Newcastle.
Attention will be paid to whether Jack Grealish and Phil Foden make the starting line-up after both were left on the bench at St James’ Park over an apparent disciplinary issue.