player steadied her game to take the following two games before losing the set.
Set two remained closely contested before Williams committed several additional errors
while Bencic remained aggressive to lead 6-5 before closing out the set.
Bencic continued her consistent play while Williams committed several errors as the Swiss held serve to take a 3-0 final set lead.
The American then hit a down the line forehand long on breakpoint to drop serve and trail 0-4 as she delivered more tennis well below her best level after two hours of play.
Then with the American’s 43-1 match record on the line, Williams struck several baseline winners and aces to win four or the next five games but still trail 4-5 as Bencic double-faulted on breakpoint.
Williams, who’d been 15-0 in three set matches this year, struck an ace down the tee to lead 15-0 in the final game of the match.
The American then netted a down the line forehand volley to reach 15 all before Bencic struck a down the line backhand volley winner to lead 30-15.
The Swiss netted a crosscourt backhand return to level the game at 30 all.
Williams sent a down the line forehand passing shot wide to face behind 30-40 and face match-point.
Bencic took control of the final point of the match with an aggressive crosscourt forehand before striking a down the line forehand winner to end the match after two hours and 28 minutes of play.
For the night, Williams had served below her best, striking 16 aces but also 12 double-faults.
On her second serve in set three, the American managed to win only two of her ten second serve points.
Williams is the top seed at next week’s Western & Southern Open at Cincinnati, Ohio.
And at the end of this month, the American will attempt to become the first tennis player since Steffi Graf of Germany in 1988 to win the grand slam, all four of tennis’ grand slam tournaments (the Australian Open, Roland Garros, Wimbledon and the US Open) in one year.