Budapest - Adam Peaty and Ben Proud both struck gold for Britain at the world aquatics championships on Monday as Hungary's "Iron Lady" Katinka Hosszu came close to tears.
Peaty clocked a new championship record of 57.47 seconds to defend his 100m breaststroke title and deliver Britain their first swimming gold in Budapest.
The proud 22-year-old said the sight of the Union Flag alone fires him up before he races.
"I find the Great British flag very motivating, as soon as I look at that it's game time," said Peaty.
"I love racing and doing it for my family and my mates back home, making them proud.
"It's great to have the support at home and from the crowd here tonight - they went crazy when I walked out tonight."
Peaty's victory triggered more British swimming success at the Duna Arena, as less than half an hour later Proud won the men's 50m butterfly final in a photo finish.
Proud, 22, clocked 22.75 seconds in the sprint with Brazil's Nicholas Santos, second at 0.04, with Andrii Govorov of Ukraine taking bronze, 0.09 behind.
The 2014 Commonwealth champion was seen as an outsider having finished fourth in the semi-finals and Proud only realised he had won when no-one else celebrated.
"Seeing what Adam Peaty has done, he has really taken Great Britain a step forward and made it easier for that next person to win gold," said Proud.
"Hopefully some more will follow this week."
Hosszu admitted she was bursting with emotion after retaining her women's 200m individual medley title in front of her home crowd.
The 28-year-old is the first woman to win three world gold medals in the event.
She was roared on by the passionate crowd as hosts Hungary claimed their first swimming medal.
"It was really amazing how everyone was supporting me in red, white and green, when I got out of the pool, I couldn't believe it," Hosszu said.
"Thank you for the experience, it was unforgettable - I almost cried."
Sweden's Sarah Sjostrom was surprised to come close to her own world record in becoming the first woman to win four golds in the women's 100m butterfly.
The 23-year-old clocked 55.53 seconds, a new championship record, just 0.05 off her world record set at the Rio de Janeiro Olympics last year.
"I was very surprised to see I was so close to the world record," she said.
"It felt like I was going a bit slower than I did yesterday (in the freestyle relay), so maybe butterfly is about being relaxed then you can go even faster.
"With these times in the first 50 metres in the 100m fly I feel very excited for the 50m flys later this week and also for the 50m free."
Sjostrom is the first reigning Olympic champion to add the world title in the discipline.
She broke the 100m freestyle record on Sunday, in the women's 4x100m relay, when she became the first woman to swim under 52 seconds.
Her victory in Budapest mirrors her 2009 triumph as a 15-year-old when the world championships were held in Rome.
She also won the event in 2013 and 2015, but Sjostrom is eyeing more gold in Budapest with the 50m butterfly, plus the 50m and 100m freestyle races still to come.
Results from the swimming finals at the World Aquatics Championships in Budapest on Monday:
Men's 100m breaststroke
1. Adam Peaty (GBR) 57.47
2. Kevin Cordes (USA) 58.79
3. Kirill Prigoda (RUS) 59.05
Women's 100m butterfly
1. Sarah Sjostrom (SWE) 55.53
2. Emma McKeon (AUS) 56.18
3. Kelsi Worrell (USA) 56.37
Men's 50m butterfly
1. Ben Proud (GBR) 22.75
2. Nicholas Santos (BRA) 22.79
3. Andrii Govorov (UKR) 22.84
Women's 200 IM
1. Katinka Hosszu (HUN) 2:07.00
2. Yui Ohashi (JPN) 2:07.91
3. Madisyn Cox (USA) 2:09.71