At the Net: This week in tennis

Philadelphia, PA ( - As usual, it was yet another busy week in the world of tennis. Let's see just what happened.

U.S. and French Open champ Rafael Nadal announced he will skip the Masters events/big U.S. Open tune-ups in Toronto and Cincinnati because of a right wrist injury suffered this week during practice. The Spanish great plays left- handed, of course, but needs the right wing for that booming two-handed backhand.

Rafa was last year's Canadian Masters champion, in Montreal, and is a three- time winner at the third-oldest event in tennis (Wimbledon, U.S. Open) and was also the reigning champ in Cincy. He expects to return in time for the 2014 U.S. Open in four weeks.

Taking a page from Nadal's injury book, Li Na announced she will skip the big Canadian event in Montreal, Cincy, and the U.S. Open, where she reached her first semifinal in the Big Apple last year. The Chinese star titled in Cincy two years ago and was a runner-up in Montreal, also in 2012.

The 32-year-old captured her second Grand Slam title at the Aussie Open in January, but has been slowed by a sore right knee since March (and her results have shown that).

Rising star and Roland Garros runner-up Simona Halep will replace Li at No. 2 in two weeks.

Note: Eleven women have reached a career-high No. 2, they were/are: Virginia Wade, Billie Jean King, Andrea Jaeger, Conchita Martinez, Jana Novotna, Anastasia Myskina, Svetlana Kuznetsova, Vera Zvonareva, Petra Kvitova, Agnieszka Radwanska and Li.

Serena Williams returned to action this week for the first time since stunningly losing to Alize Cornet in the third round at Wimbledon in late June. We don't necessarily remember Serena losing to Cornet, as our best memory of Serena at Wimbledon 2014 was that bizarre behavior/retirement in a doubles match there with her big sister, V.

At the time of this article, the world No. 1 and 17-time Grand Slam champ Serena was into the quarterfinals in Stanford, where she was a back-to- back champ in 2011 and 2012.

Former No. 1 Caroline Wozniacki announced she has designs on running in the New York City Marathon for charity in November. The recent Istanbul Cup titlist has never competed in a distance running event, but after flirting with the idea for quite some time, the amicable Dane decided she needed to push her athletic boundaries and perhaps enhance her blossoming- once-again tennis game.

Good luck, Caro.

The fastest serve ever struck on the women's tour occurred this week when 2013 Wimbledon runner-up Sabine Lisicki smashed a 131 mph one in a losing effort against former No. 1 Ana Ivanovic in Stanford. Ivanovic was able to get her racquet on Lisicki's monumental blast, but her attempted return was unsuccessful.

The old record was held by Venus Williams, at 129 mph.

A retired Andy Roddick wanted to play his first ATP-level tennis, albeit of the doubles variety, at the U.S. Open later this month, but the USTA told him it was a no-go. A-Rod was hoping to play alongside close friend and the all- but-retired Mardy Fish in Flushing ... but anti-doping rules won that match.

The problem is that Roddick isn't allowed to compete because he hasn't re- entered tennis' drug-testing program since his official retirement early last year, a few months after his final official match at the 2012 U.S. Open.

Maybe next year, Andy?

Another former No. 1 star, Victoria Azarenka, celebrated a birthday on Thursday, but that was spoiled by the aforementioned Venus, who notched a straight-set second-round victory against Vika in Stanford.

For the record, Azarenka turned 25 and is currently down to No. 10 in the world after opening the year at No. 2. She missed several months of action with a foot injury and is still trying to work off the rust from that inactivity.

She's 1-3 since returning to action last month and has dropped five of her last six matches, dating back to the Oz Open in January. It's starting to look like a lost season for the two-time Aussie Open champ and reigning two-time U.S. Open runner-up.

And Roger Federer passed two million followers on Twitter.

See ya next week...