He didn't make it out of the heats in each of his three races -- the 400m, 200m and 100m freestyle -- and withdrew from the 1,500m freestyle scheduled for Saturday.

Park, the 2008 gold medalist and 2012 silver medalist in the 400m free, finished 10th in the heats and didn't qualify for the final this time. He'd won silver in the 200m in each of his past two Olympics, but ranked only 29th to miss the semifinals.

In the 100m, Park tied for 32nd. He then pulled out of the 1,500m, citing his lack of training for the long-distance event.

The 26-year-old said he'd like to compete in his fifth Olympics in Tokyo four years from now.

Park almost never made it to Rio.

He served an 18-month doping suspension that ended in March this year. When it ended, Park was ineligible for the Rio Games because of a Korean Olympic Committee rule barring athletes from representing the country for three years after the end of their doping suspension.

Park challenged the KOC rule at the Court of Arbitration for Sport, which upheld Park's appeal on July 8, the final day to submit Rio swimming entries.

He managed to get into only two competitions this year, and Park pointed to his lack of overall preparation as the main reason for his struggles here. (Yonhap)