Trott looking to repeat Olympic omnium win over dangerous American Hammer
Olympics bronze medallist Annette Edmondson fourth, just one point further back.
Trott is attempting to win an incredible sixth title at a major championships in the space of just 24 months.
Contender: Sarah Hammer, who Trott beat to the title at London 2012, leads the Brit by five points
She finished third in the flying lap before she came home 10th in the points race, leaving her needing to perform well in the elimination.
Trott, whose boyfriend Jason Kenny was dumped out of the sprint in disappointing fashion last night, duly won but Hammer was the last rider to go out.