ST. ANDREWS, Scotland --
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The South African led from the first round and finished with a 22-under total of 266 to hold off
"It's just awesome to win an event at St. Andrews as I have really dreamt of this moment all my life," said Grace, who shot a spectacular first round 60 at KIngsbarns.
It was Grace's fifth victory of the year overall after also winning a Sunshine Tour event at Fancourt in South Africa.
Another South African, George Coetzee, equaled the Old Course record that had been set on Thursday with a 10-under 62 for a share of fifth place.
The 24-year-old Grace is the youngest winner of the tournament and his $800,000 first prize moves him to third in the Race to Dubai money list.
Grace arrived in Scotland ranked 49th but will now make the top 40 when the rankings are adjusted Monday.
Olesen kept the pressure on Grace throughout the day, reaching the turn in 33 -- three shots better than Grace -- to reduce the lead to just one stroke.
Grace dropped another shot at the par three 11th before regaining control with three straight birdies from Nos. 12-14, including a 10-foot putt at the 13th.
Grace had a bogey five at the 17th Road Hole but kept his nerve to become the first player in the 40-year history of the European Tour to win his first four events in the same season.