City have lost eight of their last 11 games in all competitions, winning just once in that sequence, and fallen nine points behind Premier League leaders Liverpool.
The Premier League champions, who have also played a game more than Arne Slot's table-toppers, now face a tough test at Villa Park on Saturday.
But Villa manager Emery, said of City manager Guardiola, a fellow Spaniard: "He's the best. I'm a little bit surprised (about Manchester City's form), but it's football.
"It's a very tough match and an exciting match for us. We're respecting them a lot.
"Each team is giving us a lot of information about how we are and how we are facing them. (On Saturday) we face the best team from the last few years, clearly, in the Premier League.
"Maybe they're not being consistent because of different circumstances, but they are the best and their coach is the best.
"They will again be getting the good performances and they have time to be a winner again in this competition."
Seventh-placed Villa are two points and two positions below City following a late defeat at Nottingham Forest last weekend.
Forest scored in the 87th minute and again in added time at the City Ground to win 2-1 and end Villa's run of three consecutive victories in all competitions.
"We are being consistent, but to be in the top level we need more in everything," former Arsenal, Sevilla and Paris Saint-Germain coach Emery added.
"We are patient with our process. We are accepting everything in our way, trying to get better.
"Tactically, emotionally, mentally, we are trying to get experiences, winning and sometimes losing, trying to be positive as well."
