Notes: Weak field with no Top 10 and only two Top 20 participants…wildcards went to Aussies James Duckworth, Matthew Ebden and John Millman…Jo-Wilfried Tsonga and Richard Gasquet pulled from the event…Aussie intrigued with Tomic opening against countryman Marinko Matosevic…Top-seeded Isner a question mark after inuring his knee at the Hopman Cup…No. 2 Simon after a bye likely looking at a tough match-up against veteran and 2012 winner Jarkko Nieminen…Returning champions in the field are Nieminen (2012) and Simon (2011).

Just when you thought the injury-o-rama in women’s tennis couldn’t get any worse, the race for the No. 1 ranking imploded on Wednesday at the Sydney event where world No. 1 Caroline Wozniacki was injured during a loss that could have consequences for her Australian Open.

The men and the women gather this week in Sydney for the Apia International, where No. 2 seed Petra Kvitova can claim the world No. 1 ranking if she can navigate a field containing No. 1 Caroline Wozniacki. In fact the women’s field is so strong that No. 10-ranked Andrea Petkovic finds herself unseeded.

Two players on the sidelines are trying to figure out how to tweak their games in time for the Australian Open — both dealing with equipment issues. Maria Sharapova switched from her long-time Prince racquet to a multi-million sponsorship with HEAD, but last week lost early in her only WTA warm-up event. This week world No. 1 Caroline Wozniacki debuted her cash-grab switch to Yonex, losing her opening-round match. Wozniacki vaulted to No. 1 behind her long-time association with her Babolat racquet. Before the event, Wozniacki and her Yonex won one game off Vera Zvonareva in an exhibition match.

Notes: (8) Lu opens against Simon, and (6) Lopez vs. (WC) Del Potro; other wildcards to Brit James Ward and Aussie Matthew Ebden; Baghdatis beat Gasquet in last year’s final; Del Potro makes his first tournament appearance since October and only his third in the last 11 months after a right wrist injury that required surgery; American Donald Young lost in the qualifying as did Aussie Carsten Ball; seeds Querrey, Gulbis and Lopez have losing career records in Sydney; the Bryan brothers, winners in 2009, are the top seeds in the doubles; Baghdatis, the only returning champ in the field, is looking to become the first back-to-back winner since James Blake (2007-06); Pete Sampras and Lleyton Hewitt (twice) won back-to-back titles, but no one has one three in a row in Sydney in the Open Era.

The list of floaters almost as impressive as the seed list; tough openers include Kirilenko vs. Cibulkova (winner to face (1) Wozniacki), (5) Schiavone vs. Kleybanova (winner to likely face Hantuchova), possible (3) Clijsters vs. Petrova 2nd rd., former world No. 2 Kuznetova vs. (WC) Dokic, winner to face (4) Stosur vs. Wickmayer winner, (6) Jankovic vs. Rezai, and (2) Zvonareva vs. winner of Pennetta vs. qualifier; 7 of the Top 10 players present in Sydney; Elena Dementieva (now retired) beat Serena Williams (now injured) in the 2010 final…Clijsters (2007, ’03) is the lone returning champ in the field, in addition to the 2008-05 runner-ups Kuznetsova (2008), Jankovic (2007), Schiavone (2006), and Stosur (2005); 11 former No. 1 players have won the Sydney title.

“It’s just a little pain and the strapping usually helps the pain go away sometimes,” Serena said.

Notes: Should be called the Spanish Open with four Spaniard leading the seeding and five seeded total.

Roger Federer isn’t above some mind games going into the Australian Open, saying that defending champion Novak Djokovic may have made a mistake switching from Wilson to HEAD right before a Grand Slam: “I mean it’s tough because there’s always a factor with the weather, how do you play, day form, you know, other contenders, the pressure, now a new racquet,” Federer said on Djokovic defending the Aussie Open title. “I’m quite surprised he made a switch like this in the best phase of his career. He can for sure play good tennis, but I think when it comes down to the crunch you just have that bit of a doubt maybe, because you are not quite that comfortable with that racquet. But we’ll see what happens. It’s going to be a big test for him.”…