Since joining Manchester City in the summer of 2016, Guardiola has dominated the English game, winning four Premier League titles, four League Cups and one FA Cup.
The Champions League trophy however remains elusive, with City coming agonisingly close over the last two seasons.
They lost the 2021 final 1-0 to Chelsea and were just seconds away from reaching another showpiece last season until a memorable late comeback from Real Madrid dumped the English champions out at the semi-final stage.
Despite losing the likes of Raheem Sterling and Gabriel Jesus this summer, City have bolstered their forward line by bring in Erling Haaland from Borussia Dortmund.
Haaland marked his Premier League debut with two goals against West Ham United last weekend and Capello believes the Norwegian is the final piece of the puzzle for Man City to finally get their hands on Europe's premier club competition.
"This year there is a favourite for me: Manchester City," the ex-England and Juventus manager told Il Mattino. "There is no race.
"They finally have a powerful centre-forward in Haaland. He has power and speed.
"I saw the match against West Ham and I realised that this time Guardiola has no excuse: he has to win the Champions League.
"Even if, in the end, they'll tell him that he [only] won the Champions League first with [Lionel] Messi and then with Haaland."
Guardiola has not won the Champions League since 2011 when his Barcelona side defeated Manchester United 3-1 in the final at Wembley.