By Martyn Herman

RIO DE JANEIRO (Reuters) - Three days is all it took to erase any lingering doubts about Britain's domination of track cycling.

By the time darkness falls in Rio on Sunday the powerhouse nation will have won four of the six gold medals up for grabs so far with the promise of more to come.

At this rate they will match, or even better, the seven gold medals they won on the boards of Beijing and London.

All after the year began with question marks over the form of some of the riders and continued with the resignation in April of the team's technical director Shane Sutton over allegations of sexual discrimination.

Olympic sprint champion Jason Kenny was one of the riders under scrutiny, but on Saturday he set up an all-British individual sprint final against Callum Skinner -- the set to go head-to-head after winning team gold on Thursday.

Kenny, chasing a fifth Olympic gold, scraped past Russia's Denis Dmitriev after losing the first leg of their semi-final while Skinner, who anchored the team victory on Thursday against New Zealand, saw off Australia's Matthew Glaetzer.

Shortly before that the women's team pursuit squad of Laura Trott, Katie Archibald, Elinor Barker and Joanna Rowsell-Shand crushed the United States in the final, shattering the world record they had set earlier in the day in the heats.

That followed the men's team pursuit quartet's thrilling race to gold against arch rivals Australia on Friday, when Bradley Wiggins took his Olympic medal tally to eight, more than any other British Olympian.

Trott became the first British woman to win three Olympic golds on Saturday and will be favorite for a fourth when the omnium event she won in London begins.

Road great Mark Cavendish is also in contention for the men's omnium title while the men's keirin offers another golden opportunity for the team.

American Sarah Hammer has come off worse against Britain more than she would care to remember, and it happened again in the team pursuit final where they trailed in two seconds back.

"Every single nation here, we all feel a little bit like underdogs to the big machine that is British cycling," she said.

Trott did not disagree.

"It went well today," she said of the team pursuit gold, a repeat of their victory in London when the U.S. also trailed in a distant second.

"We felt like a machine, a well-run machine," she said.

(Reporting by Martyn Herman; Editing by Meredith Mazzilli)