Laura Trott's defence of her women's omnium title appeared a more distant prospect after the fourth of six disciplines on the fifth and final day of the Track Cycling World Championships in Minsk.
The 20-year-old Olympic champion was third overnight, five points adrift of London 2012 silver medallist Sarah Hammer of the United States, who consolidated her advantage with victory in the three-kilometre individual pursuit.
Hammer clocked three minutes 31.550 seconds in an event in which she won the world title on day one, with Trott's 3mins 34.761secs good enough for third.
It means with the scratch race and 500metres time-trial remaining, Hammer leads on 10 points, seven points ahead of third-placed Trott.
Poland's Katarzyna Pawlowska is second on 16 points and Australia's Annette Edmondson fourth on 19.
