Team GB's Matthew Walls won his first Olympic gold medal in the men's omnium on Thursday after an early attack in the final 100-lap event.
Walls was consistent throughout the four-part event, winning the scratch race earlier in the day and was tied at the top with world champion Benjamin Thomas and Dutchman Jan Willem van Schip.
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"Coming in here, everything was a bit of an unknown," Walls said. "The last track race I did was the European Championships last year, which is a long way away. I came in knowing I was in good shape. I didn't know how it would translate to the track or my tactics from the track, it's been a long time since I have raced."
"I came into the scratch race feeling good and won it. I thought then, 'I have a chance now as long as I play it smart.' I knew I had the legs and it worked out."
Meanwhile, Walls' teammate Jason Kenny, who has six Olympic gold medals, was eliminated in the quarterfinals of the sprint by Dutch flier Harrie Lavreysen.
The 33-year-old battled his way through to the last eight after he needed a repechage win in the previous round, but Kenny was no match for world champion Lavreysen who powered past him for comfortable wins in both races.
Holly Bradshaw won Team GB's second track and field medal of the Tokyo Games as she claimed an unexpected bronze in the women's pole vault.
Bradshaw cleared 4.85 metres to secure Britain's first-ever medal in the pole vault. The 29-year-old was pipped to gold and silver by America's Katie Nageotte and ROC's Anzhelika Sidorova, respectively.
"It's not sunk in. I'm almost emotionless because I don't know what emotion it is I'm feeling, it's relief, pure enjoyment and excitement," Bradshaw said.
"I'm proud of myself for sticking with it. I knew I could get it one day, I just can't express how grateful I am to be involved in this sport and finally get an Olympic medal."
Britain's Liam Heath edged out his nearest competitor to win bronze in the defence of his Olympic men's kayak 200-metre single title on Thursday.
Heath, who has now medalled at three consecutive Games, finished the event in 35.202 seconds, just enough to finish third over Hungary's Kolos Csizmadia.
"I was maybe a bit hesitant off the start and didn't reach my potential in terms of peak speed," Heath told BBC Sport.
"I am still happy with the performance. It is hard [another medal] to put into words. It is what you work towards to be at your best for these events."
In boxing, Galal Yafai will fight for a gold medal after beating Saken Bibossinov in a split decision in the men's flyweight semifinals.
Yafai took the opening round before Bibossinov fought back to take the second, leaving everything to play for in the final round.
The 28-year-old stood firm, though, and won the semifinal as a distraught Bibossinov left the ring.
"It's ridiculous, I can't believe it, it's like a dream, Yafai said. "I've always looked to be in an Olympic final and now I'm in one -- I've just got one more hurdle to go over and that's to beat the Philippine to win gold.
"I've always dreamed about this, we would talk about it at home me and my brothers and now I'm here with them all watching me at home, my brothers, my mum, the whole world watching me now in the Olympic final and I've just got to deliver the goods and take that gold medal back home."
Dina Asher-Smith returned to competition as Team GB won their women's 4x100m relay heat in 41.54 seconds, setting a new British record.
Asher-Smith had failed to make the women's individual 100m final and withdrew from the 200m with a hamstring injury.
However, she joined Asha Philip, Imani-Lara Lansiquot and Daryll Neita to set the record and beat gold medal favourites Jamaica.
Katy Marchant crashed out in the final lap of the women's keirin quarterfinals after Dutch rider Laurine van Riessen pulled out and hit Marchant's wheel.
Marchant walked away from the crash while Van Riessen was stretchered off the track after receiving medical treatment with Dutch media reporting she was later taken to hospital.
"I think that's just bike racing -- wrong place, wrong time. I hope everyone's alright that was in the crash. I think I'm alright, just a bit battered and bruised," she told the BBC.
"I needed to finish the race in case there was something that came up on the results, a relegation or anything. I'm not really sure what happened, wrong place, wrong time, I just got caught up in it.
"I'll be back tomorrow to start the sprint competition."
In the men's marathon 10 kilometre swimming, Hector Pardoe pulled out while in 20th position after being elbowed in the face.
"I was screaming and I thought I had lost my eye," he told the BBC.
"This is a brutal sport but that's not how I expected today to finish. I've never experienced conditions like that. I will be back stronger."
Information from Reuters contributed to this report.