Norrman carded a flawless closing 65 at The K Club to finish 14-under par and a shot ahead of 54-hole leader Hurly Long, with former champion Shane Lowry part of a four-way tie for third on 12 under.
McIlroy (right) began the final round two behind Long and birdied the first and fourth either side of a 90-minute weather delay to share the lead, but hit water on the seventh, 11th and twice on the 16th for a 74.
Norrman started the day six behind Long but made six birdies in the space of eight holes from the seventh and then two-putted the par-five 18th for another to set the clubhouse target on 14 under.
Long was briefly on the same score thanks to a birdie on the 12th.
Denne historien er fra September 11, 2023-utgaven av Daily Star.
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Denne historien er fra September 11, 2023-utgaven av Daily Star.
Start din 7-dagers gratis prøveperiode på Magzter GOLD for å få tilgang til tusenvis av utvalgte premiumhistorier og 9000+ magasiner og aviser.
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