Haaland headed City ahead just before the break with Kevin De Bruyne chalking up his 100th Premier League assist - and in record time.
City then doubled our lead just before the hour as Jack Grealish maintained his fine form with a close-range finish after Saints keeper Gavin Bazunu had parried his initial effort.
Grealish then turned provider as he set up an inviting cross before Haaland despatched a stunning overhead kick to make it 3-0 and become the first City player since Francis Lee in 1971/72 to claim 30 league goals in a season.
The Norwegian striker has now got 44 goals in his incredible first season at the Etihad.
Southampton reduced the deficit with substitute Sekou Mara on the mark on 72 minutes but City were not done yet.
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After De Bruyne was brought down, substitute Julian Alvarez despatched a penalty to restore our three goal cushion.
The victory saw Pep Guardiola’s side reduce the gap at the top of the table to five points with Arsenal next in action on Sunday afternoon away at Liverpool.
And it put us in great heart ahead of Tuesday’s big Champions League quarter final first leg tie at home to Bayern Munich.
View the best images from an impressive victory via our gallery below.
