Swimming in the sixth lane, Park had the fastest reaction time at the start with 0.62 second, and was in the lead after the first 100m at 54.04 seconds.

Sun, racing next to Park in Lane 5, then started to make his charge. He moved 0.14 second ahead of Park at the 150m turn, and widened the gap to 0.65 second at the halfway point at 1:50.87.

Sun then began putting some serious distance between himself and the rest of the pack. Park dropped to third place after the 250m split, with Horton now ahead of him and Sun 1.53 seconds clear. Park slipped another notch to fourth place at the 300m point, with Detti moving into third.

Sun led comfortably at 350m, after posting an impressive, 27.59-second split. Park, still in fourth place, was now 3.18 seconds back, with virtually no hope of winning the gold.

Park made his patented last spurt and had the fastest split over the final 50m at 26.43 seconds, but it was not enough to put the South Korean on the podium.

Park came into the final with the fifth-fastest 400m time of 2017, with 3:44.38, and actually matched that time in the final as he came up short of winning a medal.

Sun won his third straight 400m world title. Prior to Sunday, the Chinese star had the best 400m record of the season at 3:42.16.

Heading into Budapest, Park had won 11 international titles since the 2016 Rio de Janeiro Olympics, where he missed the finals in the 100m, 200m, and 400m freestyle races. Park had earlier served an 18-month doping ban, and when the suspension ended, he challenged the South Korean Olympic committee at the Court of Arbitration for Sport over his national team eligibility.

Park won the legal battle but submitted a dreadful campaign in Rio. There were whispers that Park was finished as a world class swimmer, but he slowly made his way back to relevance in the months that followed the Olympics.

Park is also scheduled to race in the 200m and 1,500m freestyle in Budapest later in the week. (Yonhap)