The world number four Venus Williams has withdrawn from next week's $2.8 million WTA tennis event in Montreal due to a nagging left knee injury that has frustrated her US Open preparations.
The US veteran also withdrew from this week's event in Cincinnati, meaning she will join her sister Serena in missing the two top tune-up events for the year's final grand slam tournament that begins on August the 30th in New York.
The seven-time grand slam champion has not played a top-level singles match since she was ousted from the Wimbledon quarter-finals by 82nd-ranked Tsvetana Pironkova of Bulgaria in late June.
The only remaining US Open warm-up event possible for either Williams sister would be at New Haven in the week before the US Open.
