Manuel Pellegrini says Pep Guardiola got a wake-up call in his first year of coaching in the Premier League but he "has no doubt" his successor at Manchester City will do well.
Pellegrini guided City from 2013 until 2016 and won the Premier League in his first season in charge.
He also led City into a Champions League semifinal tie against Real Madrid in the 2015-16 campaign, with the Spanish giants winning that before lifting the trophy.
Guardiola, who had plenty of success at Barcelona and Bayern Munich, took the reins last summer and led City to a third-place finish in the league while his side crashed out of the Champions League in the round of 16.
"I think my work during the three years I was there was more valued after what City did last season," Pellegrini, who is now coaching Chinese Super League club Hebei China Fortune FC, told Futbol Tactico magazine.
"It's not easy to win the Premier League and to reach the Champions League semifinals. Perhaps many thought that with Pep's arrival, City were going to win [the league] by a 15-point margin, and in England it doesn't work like that."
City have enjoyed an unbeaten start to this season and are level with Manchester United on 10 points at the top of the domestic standings after four rounds, while they began their Champions League Group F campaign with a 4-0 triumph at Feyenoord on Wednesday.
Pellegrini coached Real Madrid in the 2009-10 campaign, a season in which Guardiola steered Barca to the La Liga title.
The former Villarreal coach does say Guardiola, who won a total of 21 titles during his coaching spells at Barcelona and Bayern, is the right man for the City job.
"I have no doubt he will do well because Pep is one of the best coaches there is today," Pellegrini said. "But the Premier League is more competitive than any other league and it's not easy to win everything."