Every week there's a lot happening on the WTA - on the court, off the court, by the numbers, even a few tweets... catch up on it all in this week's WTA Diary.

Match(es)
Usually this spot in the Diary is reserved for the week's most nail-biting, nerve-jangling and drama-packed match. This week, however, it's going to Serena Williams for her blue clay brilliance in Madrid.

Nearly a decade after picking up her last European clay court title, Serena produced some jaw-dropping tennis to defeat (among others) Caroline Wozniacki, Maria Sharapova and Victoria Azarenka en route to the title.

Watch the highlights from the American's Madrid masterclass in our video section.

Out Of The Blue
Whether it was the new surface or just one of those weeks, there were more than a few eyebrow-raising performances in the Spanish capital. And no one raised eyebrows higher than Lucie Hradecka, who, after coming through qualifying, took out defending champ Petra Kvitova and clay queen Samantha Stosur before finally running out of steam against Serena in the semifinals.

Dropping Like Flies
It was a humbling week for doubles' big guns in Madrid. The top three seeded pairings all failed to make it past the quarterfinals, with the biggest shock coming on Tuesday when Liezel Huber and Lisa Raymond lost a barnburner to wildcards Dominika Cibulkova and Janette Husarova.

The top seeds' surprise defeat opened the way for Sara Errani and Roberta Vinci, who defeated Ekaterina Makarova and Elena Vesnina for their fourth title of the season.

Not So Blue
While the blue clay has been getting mixed reviews from the players, it has gone down as storm with those watching on TV, including one former World No.1...

@Dinarik27 (Dinara Safina)
What do u think about blue clay at @MutuaMadridOpen?? I don't know how it feels to play on it, but looks great on TV!!! I ❤ it!!!

Around The Grounds
Want to see a photo of top WTA doubles team Yaroslava Shvedova and Galina Voskoboeva with a man in a luminous green headband? Of course you do. Click here to see that and a whole host of other off-court shots from Madrid.

Having A Ball
Ever wondered what happens to tennis balls once they pass their sell by date? Well, those ever-resourceful Canadians have thought up a rather ingenious way to use them to increase classroom productivity in schools. Confused? Don't worry, all is explained here.

Always Look On The Bright Side Of Life
After an injury and illness-ravaged few years, most would expect Karin Knapp to have a sizeable axe to grind with the tennis gods. Knapp, though, is not one for grudges, and is just happy to be back on court and enjoying her tennis again.

Back On Track
Another player who has endured a few years in the tennis wilderness is Melanie Oudin. However, after a productive few weeks on the USTA Challenger Circuit, she seems to have finally turned a corner. Now training at the Billie Jean King National Tennis Center in New York, the 20-year-old totted up a 7-2 win-loss record in Dothan, Charlottesville and Indian Harbour Beach, thus helping her secure one of the USTA's French Open wildcard spots.

"After the year I had last year, I decided that probably it would be smart to make a change," Oudin said. "I starting with the USTA in Boca Raton, which was a good change for me. It was definitely a fresh start. I felt a lot better about everything. I think I definitely found the place I should be training at."