Defending champion Maria Sharapova will make her first appearance since Wimbledon at the San Diego Classic this week as she once again tests her long-standing shoulder injury.
The world No. 2, who beat Kim Clijsters in last year's final to capture the hardcourt title here, has been dogged by the injury problem since the spring.
Pain-killing shots helped her to the French Open semi-finals and a Wimbledon fourth-round loss to Venus Williams.
Following the wet fortnight at the All England Club, the 20-year-old Russian underwent a precautionary scan and controversially pulled out of Russia's Fed Cup semi-final win over the US.
Despite failing to win a trophy so far this season, and with her US Open title defense approaching, Sharapova does not seem worried.
"I'm 20 years old, I've won two Grand Slams. I've been No. 1 in the world," she said.
"I've got plenty more years to either win matches or find confidence," she said.
Serb Jelena Jankovic, who won a surprise Wimbledon mixed doubles title with Jamie Murray, has played just one Fed Cup rubber indoors since the All England Club.
She will get back on cement for the first time since March in Miami.
Along with the other eight leading seeds, she has a first-round bye at what will be the last edition of an event which has fallen victim to the WTA calendar shake-up.
Russians hold half of the top eight seedings, with Anna Chakvetadze at three, Nadia Petrova fourth and Dinara Safina eighth.
Wimbledon finalist Marion Bartoli of France will try to put behind last week's opening-match disappointment at Stanford when she was defeated by Lilia Osterloh.
The Frenchwoman has admitted to still being tired and overwhelmed by her surprise Grand Slam performance this month.
Slovak Daniela Hantuchova takes the sixth seeding with Martina Hingis at seven and playing for the first time since a back injury which hampered her Wimbledon.
Wimbledon champion Venus Williams, who will represent her family after sister Serena withdrew with her thumb injury, last played the event in 2002 when she lifted the title with a win over Jelena Dokic.