South Korean swimmer Park Tae-hwan is worried that time may just be his biggest enemy as he gears up for the Rio de Janeiro Summer Olympics next month.

Still, it doesn‘t mean he has lost any hope of contending for a medal.

Park returned to South Korea Thursday from his training camp in Australia. He only secured his Olympic berth last Friday, as the Court of Arbitration for Sport (CAS) ruled him eligible for Rio and lifted a Korean Olympic Committee (KOC) ban imposed on the swimmer based on his doping history.

Between his suspension and the legal fight over the Rio ban, Park has been in just two competitions this year -- the South Korean Olympic trials in April and the Swimming Australia Grand Prix earlier this month. His first Olympic race, the 400m freestyle, looms on Aug. 6.

After landing at Incheon International Airport, Park said he received the news of the CAS decision with mixed emotions: he was happy that he was going to his fourth consecutive Olympics, but he also started worrying about the short time left until Rio.

Along the way, though, Park said he has tried to stay positive.

“I know I haven’t had much time to prepare, but I‘ve been training really hard over that short period of time,” Park said. “And I believe my hard work will pay off and I will be able to put together good performances. The most important thing will be to compete with confidence.”

Park is the 2008 Olympic gold medalist and a two-time world champion in the 400m freestyle, and it remains his main event. His best 400m time of the year, 3:44.26 set at the Olympic trials, only puts him in sixth place in the world this season.

Mack Horton of Australia made the fastest 400m freestyle time in 2016 at 3:41.65. Sun Yang of China, the 2012 Olympic 400m free champion, is next with 3:43.55.

At his most recent event in Australia, Park finished third in the 400m free at 3:49.18.

Park said he hadn‘t initially planned to enter that competition until the last minute and he saw it as merely a part of his training regimen.

“It was going to be my last competition before the Olympics, and though I am a bit disappointed about the record, it’s really nothing to worry about,” he said. “It wasn‘t the Olympics.”

Park, 26, said he is concerned about something else -- that he hasn’t been able to get into competitive races. Prior to the 2012 Olympics, where he won silver in each of the 200m and 400m freestyle, Park competed at the 2011 world championships and the 2010 Asian Games. It‘s a much different story in 2016.

“I am worried about it, but I don’t want to make it an excuse for not doing well at the Olympics,” Park said. “The decision (by the CAS) was reached at the last minute, but at least I‘ll be going to the Olympics.”

Unlike in London, where he was the defending 400m champion, Park will be the one chasing other contenders in Rio. And the situation suits him just fine.

“I’m trying not to put pressure on myself, because I am a little behind the pack in the 400m this year,” Park said. “If I can have a good race in the heat and keep at it through the finals, then hopefully it will lead to a medal.”

Park will leave for Orlando, Florida, on Sunday to set up his pre-Olympic camp, and will arrive in Rio on July 31. (Yonhap)