MONZA, Italy -- Defending champion Rikard Karlberg of Sweden led local favorite Francesco Molinari by 1 stroke in the first round of the Italian Open Thursday.
Karlberg shot a 7-under 64 at the Golf Club Milano, next to Monza's Formula One circuit.
Thunderstorms delayed play for several hours and a good chunk of the field did not complete their rounds, or even start.
Robert Karlsson of Sweden and Adrian Otaegui of Spain were tied 2 strokes back.
Italian amateur Federico Zucchetti was among several players at 4 under.
Karlberg rolled in an 18-footer for an eagle on the ninth, his final hole of the day.
"That's as good as it gets," Karlberg said. "I kept my cool even though it was a longer day. Standing over the last shot on the ninth green, I just told myself, `I'm so tired but it's just one more shot.' Pleased to execute as good as I did."
Karlberg's win in Monza last year was his first on the European Tour and he's achieved four top-10s since then, including a runner-up finish at the BMW PGA Championship.
Molinari is attempting to become the first Italian winner of the title since his maiden European Tour win a decade ago.
The first round will be completed on Friday.