John Isner in upset 2nd-round loss at Sydney

SYDNEY (AP) — Top-seeded John Isner had an upset 6-4, 6-4 loss to fellow American Ryan Harrison in the second round of the Sydney International on Wednesday.

The exit of Isner, who was promoted to the No. 1 seeding after Jo-Wilfried Tsonga and Richard Gasquet withdrew, followed two more injury withdrawals: No. 2 and 2011 Sydney champion Giles Simon (neck) and No. 6 Radek Stepanek (back).

Isner, who withdrew from the Hopman Cup mixed team competition in Perth last week with a right knee injury, lasted 71 minutes against No. 64-ranked Harrison.

The Australian Open starts Monday, leaving injured players little time to prepare for the season's first major.

In the women's draw, top-seeded Agnieszka Radwanska of Poland advanced to the women's semifinals with a 6-4, 7-5 win over Italy's Roberta Vinci.