The double world champion went into the penultimate round of this year’s series in fifth, way behind runaway sprint leader Alina Lysenko.

But the Welsh rider, 21, won the sprint event in London and was second to Russian Lysenko in the keirin.

Team-mate Katie Archibald remains on course to retain her endurance title having also produced a solid showing on Friday.

The 30-year-old Scot came in with a 27-point lead over Canada’s Sarah van Dam and was second in the scratch event to Norway’s Anita Stenberg, before claiming ninth in the elimination race.

Fellow defending champion Harrie Lavreysen remains top of the men’s sprint standings as the Dutch rider beat Britain’s Matthew Richardson in the sprint final.

The fifth and final round of the series takes place at the same venue on Saturday.