Cyclist Callum Skinner and open water swimmer Jack Burnell were in strong positions when penalties put them out of medal contention.
Skinner, from Edinburgh, dropped out of the men’s keirin after he was relegated for entering the sprint lane when a rider was already there.
The 23-year-old, who has won gold and silver medals in the 2016 Games, finished last in his heat but then appeared to triumph in the repechage. However, joy turned to despair when he was relegated for riding across the line of American Matthew Baranoski.
Skinner said: “The first race in the keirin was a bit of a disappointment. I took a while to get going. I wasn’t feeling my best but I gave it a good go. It just so happened I pulled a bit of a dodgy manoeuvre and that’s what got me relegated in the end.”
Burnell was left fuming after being disqualified from the men’s open water swimming. He was in the medal mix at the end of the 10km race but was denied in the frantic finale.
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Initially he was in a photo finish for third, behind winner Ferry Weertman of Holland, before being demoted to fifth and then disqualified altogether for a second caution from race officials.
The 23-year-old from Loughborough said: “This is the pinnacle of our sport and it’s ruined by a couple of judges, who want to stick their nose in, just because they want something to do.
“They want to be seen to be like they’re doing something. Just let the guys race. It’s an absolute outrage. There were yellow cards left, right and centre. The first yellow card that I got there was nobody either side of me. I couldn’t physically have touched anybody, even if I had had six-foot long arms.”
Britain was last night maintaining second place in the medals table as sailor Giles Scott followed in the footsteps of Iain Percy and Sir Ben Ainslie to win sailing’s Finn class, claiming team GB’s 17th gold. He merely needed to complete the race to top the podium after an eighth and second on Sunday made him uncatchable in the double-point finale.
Gymnast Amy Tinkler won bronze in the women’s floor exercise final. At 16 years old she is Team GB’s youngest athlete, but has already made her name as the 2015 senior English and British all-around champion after winning gold at last year’s 2015 British Championships – a feat which she repeated this year. She broke down in tears as she took third place.