Haaland’s latest display of his sublime predatory instincts ensured City started their Group G campaign in an emphatic fashion at the Ramon Sanchez Pizjuan Stadium.
Newsonline report that The 22-year-old put City ahead in the first half and he netted again after the interval as Phil Foden and Ruben Dias also scored.
Guardiola this week insisted City cannot pin all their Champions League hopes on Haaland.
But he has made an incredible start to his City career following his £51 million ($58 million) move from Borussia Dortmund, scoring 12 goals in just seven games in all competitions.
Haaland has scored 25 times in 20 Champions League games, a tally that now includes goals on his debuts in the competition for City, Dortmund and Red Bull Salzburg.
City’s stroll in southern Spain was just what the Premier League champions needed after the frustration of Saturday’s draw at Aston Villa.
Pitted in a group also featuring Dortmund and FC Copenhagen, City will expect to qualify comfortably if Haaland continues this kind of form.
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But only winning the Champions League for the first time will make City’s season a complete success after so many years of painful failure in the competition.
There was a touch of irony about City returning to Spain to start this year’s Champions League run after last season’s campaign ended in Guardiola’s homeland.
City suffered an agonising semi-final defeat against Real Madrid, who scored twice in stoppage time to spark an extra-time victory that left Guardiola still waiting for his first European triumph since 2011 with Barcelona.
Strong winds on their flight contributed to a delayed arrival on Monday night, but City were never in danger of being blown off course in Sevilla.
With John Stones and Kyle Walker injured, Manuel Akanji made a composed debut in City’s defence after his deadline-day move from Dortmund, while Sergio Gomez was also solid at left-back in his first start.