* Li Na advances without hitting a ball
* Radwanska shows no sign of knee injury (Includes late matches)
MIAMI, March 21 (Reuters) - Before Serena Williams planted her flag at the Sony Open it was sister Venus who ruled over the Miami hardcourts and the older of the tennis siblings signalled on Friday she was ready to reclaim the throne with a 6-3 6-3 win over Anna Schmiedlova.
World number one Serena's resume includes six Miami titles but before her reign began with a first victory in 2002 it was big sister Venus who was the Queen of South beach having hoisted the trophy three times (2001, 1999, 1998).
"I haven't won Miami (in a while) but at least I've won (in Dubai). That's how I look at it," smiled Williams, who won the in the Middle East last month. "I figure another win would be very sweet.
"My whole plan is to be playing. That's it."
Venus, at 33 the oldest player in the women's draw, joined her sister in the third round on Friday despite an uneven performance that included five double faults and 35 unforced errors.
Playing her first event since claiming her 45th career title earlier this year in Dubai, Williams displayed a few signs of rust but was never put under serious pressure by the the 19-year-old Slovakian.
"First match back, I felt good," said Williams, the former world number one who is seeded 29th in Miami. "I have been working hard since (Dubai) and I feel really confident in every situation I'm in on the court.
"I have small goals. My goal from Doha and Dubai was to be seeded here and got that.
"Then obviously my next goal is to be in the top 20 and ultimately the top 15.
"To make those steps you do have to play well and I want to win tournaments."
Elsewhere, world number two Li Na advanced to the third round without hitting a single ball when Russia's Alisa Kleybanova withdrew because of a viral illness.
After a first round bye, the Australian Open winner was supposed to lead off what has been dubbed the 'parade of champions' on the Crandon Park centre court.
Even without Li, however, the lineup remained a mouth-watering one with 17-times grand slam winner Roger Federer, world number two Novak Djokovic, Williams and defending champion Andy Murray all in action.
Kleybanova, who is fighting her way back up the rankings after battling Hodgkin's lymphoma, handed her Chinese opponent a walkover due to a viral infection.
Third seed Agnieszka Radwanska, the Sony champion in 2012, arrived in Miami riding the momentum from a runner-up finish last Sunday at Indian Wells but the Pole's participation had been left in doubt by a knee injury,
Radwanska, however, displayed no signs of distress as she thumped Swiss Romina Oprandi 6-0 6-4 in just 74 minutes.
Seventh seed Jelena Jankovic became the biggest casualty in the women's draw when the Serb was taken out 6-3 2-6 7-6 (7-2) by American Varvara Lepchenko, while 13th seeded Italian Roberta Vinci was stopped 6-4 2-6 7-5 by Czech Barbora Zahlavova Strycova.
Slovakian 10th seed Dominika Cibulkova, who lost the Australian Open final to Li, sped past Austria's Yvonne Meusburger 6-1 6-2 to reach the third round. (Reporting by Steve Keating, editing by Pritha Sarkar/Patrick Johnston)