MELBOURNE, Australia - It was being speculated about earlier in the week and on Wednesday it became a reality: Serena Williams and Andy Roddick, both Grand Slam champions and former World No.1s, will be playing mixed doubles together at this year's Australian Open. And their draw isn't easy at all.

Check out the Aussie Open mixed doubles draw right here!

Williams and Roddick drew the top seeds, Kveta Peschke and Mike Bryan, in the first round. Peschke and Bryan are two of the world's most seasoned doubles veterans, Peschke currently No.2 on the WTA's doubles rankings (and a former No.1) and Bryan currently No.1 on the ATP's doubles rankings.

But Williams and Roddick have some serious doubles credentials of their own. Williams has won 12 Grand Slam doubles titles with Venus Williams and has been No.1 in doubles too; Roddick has never been ranked higher than No.50 in doubles but has four ATP doubles titles, including the Masters 1000 crown in Indian Wells three years ago with another American star, Mardy Fish.

Williams also had some early experience playing mixed doubles. In the late 1990s, when she was still a teenager, she played five Grand Slams in the mixed discipline, finishing with a 19-3 match record (see below for details):

1998 Australian Open: fell first round w/Lleyton Hewitt
1998 French Open: runner-up w/Luis Lobo
1998 Wimbledon: champion w/Max Mirnyi
1998 US Open: champion w/Max Mirnyi
1999 Australian Open: runner-up w/Max Mirnyi

Roddick has never played mixed doubles at a Grand Slam tournament.

Katarina Srebotnik and Nenad Zimonjic, two-time Grand Slam mixed doubles champions together, are the No.2 seeds. Maria Kirilenko and Daniel Nestor are the No.3 seeds - Srebotnik and Nestor won this title last year.

A slew of WTA stars are in the draw but some of the most intriguing teams are among the unseeded contingent, most notably Jelena Jankovic and Bernard Tomic (Jankovic is a former Wimbledon mixed doubles champion, Tomic is one of Australia's biggest sports heroes at the moment) and the all-Japanese team of Kimiko Date-Krumm and Kei Nishikori. Matches begin on Friday.