Facing a break point at 30-40, she hit a second serve that was ruled out.
If he does it again, he forfeits a first serve and must hit a second serve.
Sharapova feasted in particular on Zheng's weak second serve and went 8 for 8 on break-point chances.
Williams was trailing Clijsters 4-6, 5-6 and serving at 15-30 when the baseline judge called a foot-fault on a second serve.
The 22-year-old made a sluggish start and a misfiring second serve combined with several unforced errors saw her quickly fall 0-3 behind.
The Belgian had been a set and 6-5 up when the line judge foot-faulted Williams on a second serve to give Clijsters match point.
Her second serve barely breaks 70 mph, and she hasn't mastered the maddening topspin that helped her countrywoman, Francesca Schiavone, win this title in 2010.
But Berdych had other ideas, targeting Federer's unusually brittle second serve to break in games two and six before serving out the 27-minute third set.
From match point to break point... second serve... netted by Roger.
The next game went to deuce seven times, with Sharapova repeatedly erasing a deficit, until Vesnina dumped a weary second serve into the net on break point.
Clijsters raced to a 5-1 lead, helped by her first ace of the match -- coming off a second serve -- but then missed three match-point chances at 6-3.
And perhaps against the very best his second serve has room to improve, but if you look at his stats on second serve he's one of the best behind it.
In the third set, the pair exchanged service games to love but the crucial break came in the seventh game when Agassi claimed a winner off Kuerten's second serve to lead 4-3.
Robson was able to stay with Jankovic when she made her first serve, but a statistic of just 14% of points won on her second serve held the key to the opening set.
His dominance in the first set was awesome, with the Argentine a poor second best when it came to second serve returns, primarily because of Murray's fantastic power and precision from the baseline.
He was convincing and often dominant against the rangy 25-year-old Frenchman, roaring to a 5-1 lead in taking the first set, feasting on Monfils's second serve, and fending off multiple set points before winning the tiebreak.
The Scot was not making as many first serves as he had against Nalbandian - fewer than 50% throughout the match - but he was backing up his second serve with assertive second shots and constantly threatening the Nadal serve.
I've got a second serve coming, he's got to be a little bit tight, my shots have been going in so I might as well take one good rip at it, I've got another one if I happen to miss it and that's what my mentality was.
The strength of the 2008 junior champion's game is her ball-striking and it came to her aid in game eight as she broke to love with a fizzing return of serve, but Jankovic was climbing all over the Robson second serve and she broke once again to seal the set in 31 minutes.
Hewitt, 22, made a strong start to the second set, breaking serve in the second game but Ferreira immediately broke back.
The Italian continued to take advantage of her opponent's unforced errors to start the second set with a break, and she broke the Williams serve a second time in the decisive game, sealing victory after 85 minutes with a forehand winner.
It would provide a 100-gigabyte-per-second connection to serve the growing demand for Internet, data and voice capacity between South America and the rest of the world.
They need to convince the electorate that Mrs Whitman is, in fact, unworthy to serve a second term.
The second set went with serve until a Srichaphan error put Henman 5-4 up and he sealed his 6-3 6-4 win with an ace.
Nadal looked ready to take the match to a third set after opening a 4-2 lead in the second, but his serve let him down.
Michael Mullen appeared before the Senate Armed Services Committee for a hearing to serve a second term as chairman of the Joint Chiefs of Staff.
Ancic, who had played 14 sets in his previous three matches, put up a better fight in the second set but dropped serve crucially at 5-5.
As Mr. Taylor serves his prison term, his rival warlord, Prince Johnson, will serve a second term in Liberia's senate, protected by his country's refusal to try war perpetrators.
The second set went with serve but Henman's greater experience told in the tiebreak which he won 7-5 to reach his first final since losing to Federer at Indian Wells 2004.
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