The key moment in the match was the 3rd game of the second set with Jankovic serving when Serena put up her racquet saying she wasn't ready. Jankovic has a habit of not looking at the receiver when she serves and has been accused of "quick serving" opponents on multiple occasions. According to Sports Illustrated, here's what happened:
Jankovic: “How long do I have to wait?”Serena: “Until I’m ready. I don’t play slow.”Jankovic: “But you go like this [crouching in return position]Serena: “Honestly, you got a problem? I’m not the one.”
It was quite an extraordinarily dramatic moment for a tennis match (watch it yourself here). Unfortunately for Jankovic, the end result was that she lost the next 4 games and the set after the verbal exchange. It appeared to lower the level of her play and raise Serena's. Serena ended the match by winning 12 of the last 14 games. Her first clay court win over Jankovic improved her career head-to-head to 6-4.
In the end, Serena finished the match with 39 winners to 25 unforced errors. The 2013 Family Circle Cup was her 2nd consecutive title in as many weeks, on two different surfaces. It was her 49th career title and her 3rd of the year (Brisbane, Miami and Charleston).
According to the WTA:
Only nine women have won 50 or more WTA titles, namely Martina Navratilova (167), Chris Evert (154), Steffi Graf (107), Margaret Court (92), Evonne Goolagong (68),Billie Jean King (67), Lindsay Davenport (55), Virginia Wade (55) and Monica Seles (53).Serena will almost certainly exceed Lindsay Davenport's career title haul of 55 but I doubt she will get to Billie Jean King's gaudy total of 67. The most titles she has won in a year was in 2002, when she won 8, but last year she won 7 and this year to date she has already won 3 titles before her best part of the year has arrived (summer hard court and grass). This augurs well for Serena's 2013.