MIAMI, FL, USA - Match-ups featuring Russians and Serbs are the order of the day as those on the bottom half of the draw play their third round matches at the Sony Open Tennis.
Sunday, Third Round
 Maria Sharapova (RUS #2) vs.  Elena Vesnina (RUS #32)
Head-to-head: series tied 1-1
Maria Sharapova has won 14 straight matches against her fellow Russians. Her last conqueror from her home country was none other than Miami third round foe Elena Vesnina, an upset winner in Beijing in October 2010. Of course, Sharapova is in better health and form since then, so another loss would certainly be a surprise. She showed off that form in her opener against Eugenie Bouchard, surrendering just two games. The four-time Miami runner-up has a chance to regain the No.1 ranking from Serena Williams depending on both of their results here.
Vesnina's form has also picked up since her last encounter with Sharapova, especially this season. She captured her first WTA title earlier this year in Hobart, to go along with quarterfinal appearances in Auckland and Pattaya City. She is looking for just her second Top 5 win, her first coming against then-No.5 Samantha Stosur at Charleston in 2011.
 Ana Ivanovic (SRB #17) vs. Svetlana Kuznetsova (RUS #45)
Head-to-head: Ivanovic leads 7-3
Svetlana Kuznetsova has had plenty of success here in the past and could be in the midst of another deep run. The 2006 champion and two-time semifinalist did not lose a set in her first two matches, including a second round defeat of No.18 seed Ekaterina Makarova - her 25th win at this event.
Ana Ivanovic figures to pose more of a challenge, as the former World No.1 has a big edge on Kuznetsova in their series - which began with a narrow victory right here in Miami in 2005. She has also been impressive this week, dropping just three games in her opener against Urszula Radwanska.
 Nadia Petrova (RUS #12) vs.  Jelena Jankovic (SRB #24)
Head-to-head: Jankovic leads 6-2
One would think two players who have been part of the WTA's upper echelon for many years would have squared off at least a few times recently, yet Nadia Petrova and Jelena Jankovic haven't played in five years. Before that, they did meet quite often, with Jankovic in control of their series - including a 5-0 record on hardcourts.
Jankovic won her first WTA title in almost three years in Bogotá last month, while Petrova has had plenty of recent success too - winning three titles since turning 30 last June. Jankovic's best showing in Miami was a run to the final in 2008, while Petrova was a semifinalist in 2004.