British number one Andy Murray skidded out of the Nasdaq-100 tournament on Wednesday, the same day the event lost three-times women champion Venus Williams.

Murray, champion in San Jose last month, fell to a 7-5 3-6 6-4 first-round defeat on his debut to Swiss Stanislas Wawrinka.

Venus joined sister Serena on the sidelines of their "home event" when she pulled out with an elbow injury.

Former French Open champion Carlos Moya cut through the draw, however, beating Romanian Victor Hanescu 5-7 7-5 6-4.

The second Masters Series tournament of the season marked the Tour debut of the Hawkeye line-calling system, implemented only on the showcase centre court at Crandon Park.

American Jamea Jackson became the first player to challenge a line call using the electronic technology during her 7-5 6-7 7-5 defeat of compatriot Ashley Harkleroad.

Jackson used one of her two challenges on the first point of the second set on a forehand called out. An official immediately studied a replay using the Hawkeye system and ruled that the call had been correct.

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