Pep Guardiola laughed off claims that he was the greatest coach of all time on Saturday, saying he lives with "incredible doubts" despite leading Manchester City to the treble last season.

Under the Spaniard, City became only the second English team after rivals Manchester United to win the Champions League, Premier League and FA Cup in the same season.

But Guardiola said he was "not a god" when asked if he was the greatest of all time after arriving in Japan for City's pre-season tour.

"I live with incredible doubts in my head," said Guardiola.

"If I had success in my career, I've said many times I was in Barcelona with the players that you know perfectly, I was in Bayern Munich, and we are here."

"We are building and doing something incredible I would not expect when we arrived," he added.

City have won seven Premier League titles since 2012 -- including five in the last six seasons under Guardiola.

They won their first Champions League title when they beat Inter Milan 1-0 in Istanbul last month.

Guardiola warned that "with football you cannot be sure of anything".

"Now I'm not thinking about titles or these kinds of things," he said ahead of City's game against J-League champions Yokohama F-Marinos in Tokyo on Sunday.

"Step by step, tomorrow first game, we'll see what happens at the end of the transfer window, which team we'll have."

Defender Nathan Ake said the manager was not letting any of his players rest on their laurels.

"Obviously last season was a great season for every one of us, but we also know football keeps going forward," the 28-year-old said.

"Last season is last season and we all have the mentality to go again."

Guardiola did not confirm whether Kyle Walker, a reported transfer target for Bayern Munich, would still be with City come the start of the season. 

"I want the best for my players," he said.

"Of course I spoke with Kyle and everything is right, so we'll see what happens.

"I cannot tell you anything because still he is thinking about that," he added.

He also declined to give Joao Cancelo, who spent the end of last season on loan at Bayern, any assurances.

"Joao has been so important for us in the past," Guardiola said.

"He's back here and he's part of the group. We will see what happens."

City play Bayern on Wednesday in Tokyo.

They then travel to Seoul where they will take on Atletico Madrid.

sca-amk/lb