The 25-year-old landed a birdie hat-trick from the 15th on the way to a flawless seven-under-par 63 that gave him a one-shot lead over Britain’s Daniel Brooks in bright and breezy conditions.
Sharing third position on 65 were British trio Matthew Nixon, Richard Finch and Seve Benson, Spanish pair Alejandro Canizares and Adrian Otaegui, U.S. Ryder Cup player Jimmy Walker and Swede Johan Carlsson.
Olesen is looking to claim one of the three spots for St Andrews next week that are available to those not already exempt for golf’s oldest major.
The twice European Tour winner has missed a host of cuts this year but said it was good to be back on a links layout.
“I have been struggling to hit fairways but I hit a lot offairways today,” Olesen told reporters. “I grew up in Denmark where we are used to playing in wind so that kind of helps me on links courses.
“I was ninth in the 2009 British Open at Turnberry and later that year I went close to victory in the Dunhill Links so it showed today I can still shoot low rounds.
“I hit almost every green, only missing the 18th. We didn’t have that much wind today which meant you could attack the golf course a little bit,” said Olesen.
“The warm temperatures, especially for the last nine holes, also made it a little bit easier.”
Among a sizeable group of players on 66 were American duo Rickie Fowler and Matt Kuchar, and defending championJustin Rose of England.
“That was a very satisfying start, I felt pretty calm and comfortable,” said Rose. “It wasn’t a great round but it was a very good round.
“It was a pretty stress-free day and I didn’t burn up too much energy. I felt like I left a few out there, the greens are so good so you can make some putts out there.”
Former Scottish Open winner Phil Mickelson opened with a 69.
(Editing by Tony Jimenez)