Why was Serena Williams and Petra Kvitova's last meeting historic? What happened the last time Kvitova played against a World No.1? Get ready for Thursday's matches right here...
WTA Staff

ISTANBUL, Turkey - Every day we will bring you 10 things to look for on the court in Istanbul - stats, nuggets, upcoming milestones, head-to-heads. Get your fix on all of that for Day 3, right here.

(play begins at 5pm Istanbul time - watch live here)

(for round robin standings and scenarios see Match Notes in the Press Center)

(4) Li Na (CHN #5) vs. (7) Jelena Jankovic (SRB #8)
Head-To-Head: Li leads Jankovic, 5-4.

In their last meeting, Li lost only three games and won 15 points in a row at one point.
~ Li and Jankovic have a close head-to-head but their last meeting was anything but close, as Li beat Jankovic in the fourth round of the US Open this year in 57 minutes, 63 60. She won 15 points in a row from 5-3 first set to 2-0, 40-0 in the second set - Jankovic won the next point but no more games.

These two have a WTA doubles title together.
~ Li and Jankovic won Birmingham together in 2006. They each only have two WTA doubles titles, Li winning Tashkent in 2000 with Li Ting and Jankovic in Toronto this year with Katarina Srebotnik.

(3) Agnieszka Radwanska (POL #4) vs. (8) Angelique Kerber (GER #9)
Head-To-Head: Radwanska leads Kerber, 5-3.

These two just played in back-to-back weeks in the Asian swing - and split them 1-1.
~ Kerber beat Radwanska in the Tokyo quarters; Radwanska beat Kerber in the Beijing quarters.

Radwanska has a losing record against lefties this year.
~ Radwanska is 53-13 against righties this year but 3-5 against lefties (all five losses in straight sets).

Kerber is looking for her first career win at the WTA Championships.
~ Kerber went 0-3 in her first WTA Championships appearance last year (though she did come close to beating Azarenka - she held two match points) and is 0-1 so far at this year's tournament.

(1) Serena Williams (USA #1) vs. (5) Petra Kvitova (CZE #6)
Head-To-Head: Serena leads Kvitova, 4-0.

The last match these two played was a thriller AND historic.
~ Serena won their first three meetings in straight sets but barely escaped in the quarterfinals of Doha earlier this year, rallying from 4-1 down in the third set to win, 36 63 75. By virtue of that win she became the oldest No.1 in WTA history - watch the highlights and her emotional on-court interview.

If Serena wins she will have THE second-longest win streak in WTA Championships history.
~ Serena has won 12 matches in a row at this event, tied for second-longest win streak here (Evert and Seles also had 12-match win streaks). Navratilova won 21 matches in a row here from 1983 to 1987.

Serena hasn't lost a set to anyone other than Venus at the WTA Championships since 2007.
~ In her first round robin match in 2007, Serena dropped the first set to Chakvetadze then retired with a knee injury - that was the last set she has lost to anyone at this event other than Venus (since then at this event, she is 5-3 in sets against Venus and 22-0 in sets against everyone other than Venus).

The last time Kvitova played a World No.1, she won - and it was here.
~ Kvitova beat a No.1-ranked Wozniacki in the round robin portion here in 2011, 64 62. She actually has two career wins over World No.1s (she beat Safina in the third round of the 2009 US Open).

Kvitova is trying to become just the third player born in the 1990s to beat Serena.
~ Serena has only lost twice to players born in the 1990s - once to Wozniacki and once to Stephens.

More from Wednesday...
Video: Highlights & Interviews
Serena Still Perfect On Radwanska
Jankovic Too Solid For Azarenka
Li Closes Out Resilient Errani
Istanbul Gallery: Serena Strikes 75
A Deeper Look: Li Vs Errani
Quotable Quotes: Istanbul, Wednesday