By Liana B. Baker

RIO DE JANEIRO (Reuters) - Inbee Park has two words for doubters who thought she should sit out the Olympics and give her spot to another South Korean: gold medal.

Park's commanding five-stroke victory in the first Olympic golf tournament in modern times was a surprise to those who follow the sport closely and knew Park had not been playing like herself this season.

Plagued by a thumb injury, she missed two months of competitive play including two majors this year. Then, when she returned to the game in a South Korean event two weeks before the Olympics, she missed the cut.

"Back in Korea, when I made my decision, a lot of people were saying maybe it might better for a fellow South Korean player to be in the field. That is understandable, but I wanted to play well this week to show a lot of people that I still can play," Park said.

Park, who adds a gold medal to seven major wins and the honor of being the youngest Ladies Professional Golf Association hall of fame qualifier at 28, was in vintage form in Rio.

She announced her arrival by firing a bogey-free opening round on Wednesday on the first day of the tournament. She went on to shoot a five-under 66 for three of the four rounds, and only stumbled with a 70 in the third round in very windy conditions.

How did Park come back from oblivion?

"I have been working with two coaches since last month. Because of the injury, my swing wasn't swinging the way I wanted and I didn't know exactly what the problem was. My new coach, my husband's friends, found some new points in my swing and we worked on that so I was hitting the ball much better than I was a couple of months ago," she said.

Golf Channel analyst Brandel Chamblee called Park's win "definitely an 'in your face victory' given all the pressure she was facing."

In the end, she can't stay mad at South Korea, especially with so many fans from her country following her on the course and chanting her name after the gold medal ceremony.

"Being able to hear the national anthem on the golf course on the 18th hole was an unforgettable moment," she said.

(Reporting by Liana B. Baker; Editing by Bill Rigby)