Britain’s Reece Dunn took silver on his Paralympic debut in the S14 100m butterfly final in Tokyo.
The Plymouth swimmer, 25, is the world champion but was beaten by Brazil’s Gabriel Bandeira by 0.36 seconds.
“I knew it would be a tough race but I’m a bit disappointed in my finish,” Dunn told Channel 4.
Fellow debutant Toni Shaw started the GB medal rush in the pool when she took bronze in the women’s S9 400m freestyle.
Dunn, who was diagnosed with autism as a teenager, made his international Para-swimming debut in 2019.
He set a world record of 54.46 seconds to win gold at the 2019 Worlds and claimed a Paralympic record in the heats.
But Bandeira was quick off the blocks and Dunn turned in third and was unable to get past his rival.
Shaw, 18, finished behind Australia’s Lakeisha Patterson and Hungary’s Zsofia Konkoly, who fought out a thrilling finish.
“I’m super happy. I was hoping for a personal best and that’s what I did so I’m really happy,” she said.
“I was very nervous but I had support from my coach and my friends and family. That helped calm me down so I was ready to swim tonight.”