MIAMI, FL, USA - After receiving first round byes, Thursday will see the seeds in the top half of the draw make their bow at this year's Sony Open Tennis. Agnieszka Radwanska and Marion Bartoli face tough matches against Hsieh Su-Wei and Andrea Petkovic, while Venus Williams takes on Kimiko Date-Krumm.
Thursday, Second Round
 Agnieszka Radwanska (POL #4) vs. Hsieh Su-Wei (TPE #38)
Head-to-head: first meeting
Agnieszka Radwanska won the biggest title of her career in Miami 12 months ago and begins her defense with a potentially tricky encounter against the wily Hsieh Su-Wei. Like Radwanska, Hsieh is more artisan than aggressor, with a veritable smorgasbord of shots up her sleeve.
After a difficult few months, Hsieh hinted at a return to form during a straight set victory over high-flying Lesia Tsurenko in the first round, and she will need to raise her game a further notch if she is to trouble Radwanska, who has lost just twice (and one of those came by way of injury) in her last 56 matches against players outside the Top 30.
 Venus Williams (USA #18) vs. Kimiko Date-Krumm (JPN #78)
Head-to-head: Williams leads 2-0
When Kimiko Date-Krumm made her Key Biscyane debut back in 1991, 25 of the players in this year's main draw were yet to be born. However, judging by her performances over the last six months, she is showing no sign of slowing down. The 42-year-old has won 24 of her last 32 matches on tour and looked particularly sharp in swatting aside Chanelle Scheepers in the opening round.
Her reward for this is a meeting with another of the WTA's evergreen stars, Venus Williams. Although she has played just two events this season, Williams' magnificent record in Miami ensures she will have a spring in her step on Thursday evening; in 13 previous appearances, the American has won a staggering 51 matches, picking up the title in 1998, 1999 and 2001.
 Marion Bartoli (FRA #11) vs. [WC] Andrea Petkovic (GER #162)
Head-to-head: Petkovic leads 3-2
Former World No.9 Andrea Petkovic faces the first real test of her latest comeback when she takes on Marion Bartoli. A succession of injuries over the past 14 months has resulted in Petkovic slipping out of the Top 100, but despite her recent inactivity she will be buoyed by her performance in the last round.
Against Bojana Jovanovski on Wednesday, she dropped just four games, and if her favored forehand continues to fire, she is certainly a very live underdog. Bartoli has had an up and down year, but, with two semifinal runs in her past three visits, is always a tough nut to crack on the Crandon Park hardcourts.