Isner loses to Harrison in Sydney
The exit of Isner, who was promoted to the No. 1 seed 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.
Copyright 2013 by The Associated Press
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