Britain's Mark Cavendish is third at the halfway stage of the omnium on his return to the track at the first round of the Revolution Series in Derby.
He trails leader Ed Clancy by 16 points with the three remaining disciplines taking place on Sunday.
Britain's Laura Trott is two points ahead of Belgium's Jolien D'Hoore in the women's omnium at the same stage.
Matt Gibson won the individual pursuit, while fellow Briton Lewis Oliva took the sprint.
On a triumphant day for British cycling, Katy Marchant followed up her time trial victory on Friday with success in the women's sprint.
Cavendish believes the omnium is his best chance of a gold medal at the 2016 Rio Olympics and earlier wrote on Twitter that he was nervous about his first participation in the event in 15 years in the Revolution Series, which carries points for Olympic qualification.
He finished a lowly 11th in the first of the six disciplines in the 60-lap scratch race, but bounced back in the individual pursuit to claim second behind Britain's Chris Latham, then put in a solid performance to take fourth in the elimination stage.
Double Olympic champion Clancy followed up fourth places in the first two disciplines with victory in the elimination. Britain's Mark Stewart lies second, two points ahead of Cavendish.
In the women's event, 2012 Olympic champion Trott won the 40-lap scratch race and the omnium elimination, but was second behind D'Hoore in the individual pursuit as they dominated the event.
The time trial, flying lap and points race will complete the men's and women's omnium on Sunday.
In the men's sprint Oliva shocked former world sprint champion Francois Pervis in the semi-final before beating Britain's Callum Skinner in the final.
The biggest surprise of the day was 18-year-old Briton Matt Gibson's victory in the individual pursuit in a world class time of 4 mins 21.2secs.
The three-day Revolution event concludes with the the keirin, Madison and the remaining disciplines in the omnium on Sunday.
After Derby, the series visits Manchester in October then London and Glasgow in November, before concluding with two more rounds in Manchester in January.