In one of the most anticipated matchups of the world aquatics championships, Regan Smith finished second to Kaylee McKeown in the women's 100-meter backstroke Tuesday in Fukuoka, Japan.

Smith, of Lakeville, led the race at the 50-meter mark but was passed by her Australian rival in the final meters. McKeown finished in 57.53 seconds to earn the world title, with Smith second in 57.78. Another American, Katharine Berkoff, was third in 58.25.

Smith was the defending world champion and Tokyo Olympic bronze medalist in the 100 back, while McKeown holds the world record and won gold in the event at the Tokyo Games. McKeown's time Tuesday was the fourth-fastest in history.

"It hurt so bad at the end, but I know I went for it,'' Smith said in a post-race interview with NBC. "I think I gave Kaylee a really great race.

"I just didn't quite have it those last few (meters). I could tell my tempo really died down there at the end, but I gave it my all. I'm proud knowing I left everything in the pool.''

After a great start, Smith swam the first 50 meters in 27.95 seconds, with McKeown just behind in 28.03. Smith was strong off the turn, but McKeown roared home to catch her late in the race. McKeown's time was a world championships record.

Smith held the world record in the 100 back for about two years, setting a mark of 57.57 at the 2019 world championships that stood until McKeown swam 57.45 in 2021.

Smith is scheduled to race three more individual events at the world championships — the 200 back, the 50 back and the 200 butterfly — plus medley relays.