(8) Petra Kvitova
Kvitova heads to Melbourne Park low on both confidence and form.
The Czech appeared to be the rising force in women's tennis when she claimed her maiden Grand Slam title at Wimbledon in 2011.
She followed up by winning the WTA's year-end tournament in Istanbul, a victory that pushed her to a career-high position of two in the world rankings, and leading her country to glory in the Fed Cup final.
But Kvitova did not return to those heights in 2012 and, in particular, has struggled to raise her game outside the major events.
Her runs to the semi-finals of the Australian and French Opens provided respite from some mediocre results in the lesser WTA tournaments.
The lefty's 2013 campaign has begun in inauspicious fashion with early exits in Australian Open warm-up events at Brisbane and Sydney with the Czech admitting: "I'm not feeling very well right now, in my confidence, but I'm always looking forward to playing grand slams and I hope everything will be better there than here."
Kvitova's record at Melbourne Park is encouraging, though; a semi-final run 12 months ago her best result in four appearances.