Pep Guardiola has said it will be "impossible" for Manchester City to match last season's treble-winning campaign.
City are preparing for their Premier League opener against Burnley at Turf Moor on Friday, just two months after lifting the Champions League trophy in Istanbul.
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And ahead of the new season, Guardiola has warned fans not to expect a repeat of their record-breaking season.
"I think it will be impossible to do what we have done last season," Guardiola told a news conference on Thursday.
"It's once in a lifetime. I said to the players: 'Forget about it, We climbed the highest mountain last season with what we have done.'
"But the last two days we came down from the mountain and we start from there. "There will be a lot, a lot of difficulties to climb the mountain as high as possible.
"Our football, our behaviours, our mentality will dictate how the season will be. In football, in sport, what we have done remains in our hearts and our minds, how nice it was, but it's over."
New signing Josko Gvardiol is available to make his debut against Burnley after missing the Community Shield defeat to Arsenal.
City have also rejected reports that Mateo Kovacic suffered a serious injury in training and the midfielder -- a summer signing from Chelsea -- is also expected to be part of the squad at Turf Moor.
"Normally the first games are difficult, especially against newly promoted teams," Guardiola said.
"They have energy and want to start well. Vinny [Vincent Kompany] knows us well. He did an incredible job and destroyed the Championship. To win, win, win is so difficult in the competition. He is going to do really, really well [in the Premier League]. It is going to be a difficult game."