Serena and Venus Williams make their long-awaited returns from lengthy injury absences at the Eastbourne grasscourt tournament from Monday in the last warm-up before Wimbledon.
Serena hasn't played since winning her fourth Wimbledon title 49 weeks ago, suffering a freak foot injury when she stepped on glass at a restaurant followed by a worrying February blood clot in her lungs which required surgery.
The one-time number one has fallen to 25th on the WTA rankings, with her elder sister Venus standing at 32.
Five-time Wimbledon winner Venus hasn't been on court since January 21 when she retired after one game against German Andrea Petkovic at the Australian Open, citing abdominal muscle problems.
She will pick up where she left off after drawing eighth seed Petkovic in the first round on the grass at this sleepy English south coast venue while Serena will play against Bulgarian Tsvetana Pironkova.
"I am so excited to be healthy enough to compete again," Serena said in a statement last week.
"These past 12 months have been extremely tough and character building. I have so much to be grateful for. I'm thankful to my family, friends, and fans for all of their support. Serena's back."
The Williams sisters have been filmed hitting at Devonshire Park but apparently shunning outside contact.
Reports on Twitter indicate that the camp ignored not only the media but also a friendly greeting shouted across the lawns by world number five Victoria Azarenka, third seed behind Vera Zvonareva and French Open champion Li Na.
Two-time 2010 Grand Slam finalist Zvonareva opens against British wild card Heather Watson with the winner of that contest to face either Venus or Pironkova.
Li faces a qualifier while Azarenka plays China's Peng Shuai. Former number one Ana Ivanovic faces rising German Julie Goerges.
The men's ATP side of the field at Devonshire Park will feature the south coast debut of former number one Lleyton Hewitt.
The Australian, who won a pair of Grand Slam titles a decade ago, will start the pre-Wimbledon week with a ranking outside of the top 100 after falling in the quarter-finals in Halle, Germany, which he won a year ago over Roger Federer.
Hewitt will start his campaign against Olivier Rochus.
Top seed is Frenchman Jo-Wilfried Tsonga, who knocked Rafael Nadal out in the Queen's club quarter-finals while Ukraine's Alexandr Dolgopolov, the 22-year-old 2010 semi-finalist, takes the second seeding.
Serb Janko Tipsarevic is third, ahead of Spain's Guillermo Garcia-Lopez and number five Ukranian Sergiy Stakovsky.