What is this U.S. Open Series and why should any of us care about it? We’re in the dog days of the tennis season – some of us are still recovering from the French Open drama and celebrating Federer’s 15. And now we’re supposed to get pumped up about the Sam Querrey vs. Robby Ginepri final in Indianapolis this weekend?

Yes! Yes, we are!

Take a look at last year. Two of this season’s top performers, Juan Martin del Potro and Dinara Safina, both won two Series tournaments in ‘08. Andy Murray, last year’s U.S. Open runner up, also won his first ever Masters title last year in Cincy. Instead of “It Must Be Love” the USTA’s tagline could be “Fresh Blood.”

The U.S. Open Series will also provide answers to some intriguing questions. Here are my Top 10 U.S. Open Series Mysteries:

1. How are Rafael Nadal’s knees, really?

2. How long will Roger Federer be on paternity leave? If he does play, will he be refreshed and relaxed or distracted and sleepy? (Speaking of Roger, click here for a run down of his US Open Series success – thanks, GTT reader, for the tip!)

3. Maria Sharapova said recently that she’s “100 percent.” Is that World Team Tennis fit or Grand Slam Champion fit?

4. With Serena Williams and Dinara Safina both playing in Cincinnati and Toronto this year, the “Battle of the Real No. 1s” is still in high gear. Will Dinara continue to dominate the smaller tournaments while Serena goes home with the big prize?

5. Will Ana, Jelena and Novak finally pull out of their Serbian Slump?

6. Kim Clijsters’ comeback – will she embarrass the field, or herself?

7. Was the Wimbledon final Andy Roddick’s last stand or a new beginning?

8. Who will be the next best American on the men’s side?

9. Will Marat Safin squeeze anything positive out of his last months on tour?

10. Who among the WTA young guns – Wozniacki, Lisicki and/or Azarenka - will be a contender in NYC?

Now that you’re dying to watch, here’s a run down of the U.S. Open Series schedule (click here for the television schedule):

July 27 – August 2:

ATP: LA Tennis Open at UCLA
Top players: Tommy Haas, Mardy Fish and  Marat Safin.
2008 Champ: Juan Martin del Potro

WTA: Bank of the West Classic at Stanford
Top players: Venus and Serena, Maria Sharapova, Elena Dementieva and Jelena Jankovic
2008 Champ: Aleksandra Wozniak

August 3 – 9

ATP: Legg Mason Tennis Classic, Washington DC
Top players: Andy Roddick, Jo-Wilfried Tsonga, Juan Martin del Potro
2008 Champ: Juan Martin del Potro

WTA: LA Women’s Tennis Championships, Los Angeles
Top seeds:  Dinara Safina, Svetlana Kuznetsova, Maria Sharapova, Ana Ivanovic
2008 Champ: Dinara Safina

August 10 – 16

ATP: Rogers Masters, Montreal
Top players: They’re all there – except maybe Roger. . .
2008 Champ: Rafael Nadal

WTA: Western & Southern Financial Group Women’s Open, Cincinnati
Top players: Almost all the top players + Kim Clijsters (not sure about Sharapova)
2008 Champ: Nadia Petrova

August 17 – 23

ATP: Western & Southern Financial Group Masters, Cincinnati
Top players: They’re all supposed to be there.
2008 Champ: Andy Murray

WTA: Rogers Cup, Toronto
Top players: EVERYBODY – including Clijsters and Sharapova
2008 Champ: Dinara Safina

August 23 – 29

ATP/WTA: Pilot Pen Tennis
Top Players: Simon/Ferrer/Dent and Wozniacki/Mauresmo/Cibulkova
2008 champs: Marin Cilic & Caroline Wozniacki

Photo by Ronald Martinez/Getty Images via usopenseries.com.