Serena Williams entered the semi-finals of the JP Morgan Chase Open with a 4-6, 6-3, 6-3 victory over Russian Vera Zvonareva on Friday.
The tournament favourite was joined in the semi-finals by her second-seeded sister Venus, number three Lindsay Davenport and number four Elena Dementieva.
Playing in front of almost 8,000 fans, Williams had to call upon all of her reserves as Zvonareva gamely kept in the match, firing winners from all over the court.
With the crowd loudly in her favour, the holder of six Grand Slams had to wait until the seventh game of the third set before her opponent cracked, the 19-year-old Russian double faulting twice and missing two easy backhands down the line to give Williams the break to 4-3.
Williams easily held her service and in the final game broke Zvonareva again, ending the match with a screaming backhand pass.
Since returning to the tour in March after eight and half months off due to a knee injury, former world number one Williams has only won one tournament.
"I got overconfident when I won my first tournament coming back and I realised it wasn't that easy," she said.
"But I'm trusting my shots more now because I'm practising more."
She will next face Dementieva, who outfought countrywoman Svetlana Kuznetsova 5-7, 6-2, 6-2 despite suffering a foot strain in the third game of the second set.
Davenport, who beat Venus Williams to win the Stanford title last week, continued her roll through California, overpowering the despondent seventh seed Nadia Petrova 6-1, 6-1.
The 28-year-old Davenport has won seven matches in a row on hard courts.
"I cannot be anything but happy with where I'm at," Davenport said. "I'm playing really well. I did what I wanted to do and any time you beat a top 10 player that easily, it's a great win."
Davenport will have a rematch with Venus Williams, who wore down 11th seed Francesca Schiavone 7-5, 6-1.
"I know she'll be out for revenge," said Davenport.
Venus blamed her Stanford defeat on 73 unforced errors and promised not to be as sloppy again.
"My whole goal is to make less errors," she said. "Any time someone plays me they have to hope I play badly to win. I'm not hoping she plays bad, I'm not hoping she plays good, I'm not hoping her forehand or backhand breaks down or whatever. I pretty much focused on what I have to do."