Great Britain's Savannah Marshall moved to within two wins of Rio 2016 qualification after advancing to the last 16 in the World Championships.
The 25-year-old Hartlepool middleweight took a unanimous decision over Azerbaijan's Elena Vystropova, who she beat to win the world gold in 2012.
Marshall will book a place in Rio by making the semi-finals in Kazakhstan.
Team-mate Nicola Adams and the Republic of Ireland's Katie Taylor begin their campaigns on Saturday.
Adams has already ensured that she will be in Brazil to defend her Olympic flyweight title after victory at the European qualifying tournament in April.
Taylor - like Marshall - must make the last four of the World Championships to book her place after a surprise defeat by Azerbaijani fighter Yana Alexseevna last month.