MASON, Ohio — Andy Roddick threw his racket at the ground in a flash of anger, unable to accept what was happening.

Only two weeks away from the U. S. Open, the top-ranked American melted down.

Fellow American Sam Querrey matched him shot-for-shot and made the biggest ones during a pair of tiebreakers Wednesday night, setting up a 7-6 (11), 7-6 (3) victory at the Cincinnati Masters.

“That first set was key for me,” said Querrey, who has won 16 of his last 20 matches.

In four afternoon matches, top-seeded Roger Federer, No. 2 Andy Murray, No. 3 Rafael Nadal and No. 4 Novak Djokovic all were winners in straight sets.