Nanning (China), Oct 4 (IANS): Reigning world all-around champion Simone Biles is expected to lead the US women's team as they launch their title defence on the first of the two-day women's qualifications of the 45th Artistic Gymnastics World Championships here Sunday.

Biles and Kyla Ross, the 2013 world all-around silver medallist, will be joined by teammates who are capable of difficult and consistent performances. They will compete in Subdivision 5, reports Xinhua.

The US won team gold at the 2011 world championships in Tokyo and the London 2012 Olympic Games. No team competition took place at the 2013 world championships in Antwerp, where the US women took eight of the available 15 individual medals.

Russia, who earned team gold in 2010 and lost their title to the US in 2011, will get an early start on their challenge to regain the top position.

Competing in Subdivision 1, Russia will rely on veteran Aliya Mustafina' s typically sturdy, elegant performances to help them stay on pace with the US team in Nanning.

Mustafina won the 2010 world all-around title, and finished third all-around to Biles and Ross at the 2013 world championships.

Medal contenders such as China, Romania and Britain will compete on the second day of qualifications, which includes Subdivisions 7-12 Monday.

The top eight teams from qualifications will advance to Wednesday's team final; the top 24 all-around gymnasts (maximum two per federation) will advance to Friday's all-around final; and the top eight gymnasts (maximum two per federation) on each of the four apparatus will advance to next weekend's respective apparatus finals.