OMAHA, Neb. (AP) — Katie Ledecky’s rivals are lining up to challenge the world’s dominant female distance swimmer at next month’s Tokyo Olympics. One of them is Ariarne Titmus of Australia. She fired off two of the second-fastest times ever in the 200- and 400-meter freestyles at her country’s trials. Ledecky answered with times that were slower in both events at the U.S. trials. With little over a month to go until Tokyo, Ledecky is searching for any edge she can find to drop precious seconds. She’s qualified for three individual events so far. Next up, Ledecky swims the 800 free on Friday in Omaha, Nebraska.