Double Olympic champion Rebecca Adlington produced a strong finish to win silver in the women's 400m freestyle final in Shanghai.
The 22-year-old was seventh at the 100m stage but battled back to clinch silver behind Italian Federica Pellegrini.
Michael Phelps, meanwhile, had to make do with bronze in his World Championships debut.
His United States team finished third in the men's 4x100m freestyle relay behind Australia and France.
The 14-time Olympic champion took the lead leg but Australia had the better of the US and also held off France to finish the race in three minutes 11 seconds.
Earlier in the day, Mansfield-based Adlington produced a much-improved performance to make the podium after only scraping into the final as the seventh-fastest qualifier.
After starting in lane one, she trailed the field in the opening stages but she soon moved through the gears and was second at the midway point.
There was no catching defending champion Pellegrini, who touched home in four minutes, 1.97 seconds, but Adlington stuck to her task to take silver in 4.04.01 ahead of Camille Muffat of France (4:04.06).
Afterwards, Adlington said she had been "quite down" after swimming so slowly in her heat.
"I tried to get in that race as much as I could and to come away with a silver medal in an event that isn't my best, I'm so pleased," she told BBC Sport.
"I stuck with Kylie [Palmer] and did my own race - I couldn't see, I saw Pellegrini at 350m because I saw feet and thought it had to be her.
"I just tried to work as hard as I could because I saw that no-one was with her so I thought I'm in with a shot of a medal here.
Adlington came back in similar circumstances to win bronze in the last World Championships in Rome in 2009.
And although her time was 2.04 seconds behind Pellegrini and outside her season's best, Adlington said she took heart from the experience.
Adlington added: "I feel like I've made mistakes this cycle. We tried a few things this year in preparation for next year and we'll learn from that."
Great Britain team-mates Jemma Lowe and Ellen Gandy made it through to Monday's 100m butterfly final.
Lowe, 21, was fifth fastest in 57.57 seconds with Gandy scraping through in eighth in 57.97.
Hannah Miley won through to the 200m individual medley final after heats that saw European champion Katinka Hosszu and multi world medallist Kirsty Coventry fail to progress.