(Reuters) - Thailand's Ariya Jutanugarn notched her fifth victory inside four months when she powered to a four-stroke triumph at the Canadian Women's Open in Alberta on Sunday.

Nine days after a knee injury forced her to withdraw during the Rio Olympics, the 20-year-old carded a closing 66, punctuating her dominant performance with a six-foot birdie at the last at the Priddis Greens course in Calgary.

Ariya, who started the day with a two-shot lead over Chun In-gee, credited her recent success to a newfound calmness on the course.

"No matter what's going to happen, I can handle it," she said after finishing at 23-under 265.

South Korean Kim Sei-young (66) claimed second place on 19-under, with compatriot Chun (69) a shot further back in third.

Lydia Ko came up short in her quest for a fourth victory in the event before the age of 20, the Kiwi finished tied for seventh on 13-under.

Ko's world number one ranking may not be safe for much longer given the recent form of number two Ariya, who did not have an LPGA victory until May. She then rattled off three successive wins.

Ariya, who won her first major four weeks ago at the British Open, was leading the Olympic tournament after the first round in Rio before pulling out during the third with a knee injury.

She considered skipping Canada but recovered quickly enough to play in Calgary, where she competed with medical strips of tape on her left knee.

"I feel really happy with myself right now," said Ariya, who squandered several excellent chances to win tournaments earlier in the year before managing to get across the finish line.

"I think my tee shots pretty good all week, and my irons getting a lot better in the last week or so."

(Reporting by Andrew Both in Cary, North Carolina; Editing by Peter Rutherford)