Serena Williams can move one step closer to tying Margaret Court for the most career grand slam singles titles when she takes on Naomi Osaka in the semifinals of the 2021 Australian Open. The match is set to begin at 10 p.m. ET on Wednesday. William Hill Sportsbook lists Osaka as a -150 favorite, with Williams listed as a +120 underdog. There are plenty of other ways to bet the match, including whether Osaka will cover the 2.5-game spread and how many sets the match will last. 

Before you make your 2021 Australian Open women's semifinals picks, you NEED to see who Gavin Mair is picking. 

Mair is the international women's tennis expert who called unseeded Jelena Ostapenko (80-1) winning the 2017 French Open, Naomi Osaka (32-1) winning the 2018 U.S. Open, Bianca Andreescu (20-1) winning the 2019 U.S. Open, plus many other spot-on calls.

Prior to the women's final in the most recent grand slam, the French Open, Mair picked Iga Swiatek to win (-163) in straight sets (+140), and he was right on both counts.

Now, Mair has broken down the latest 2021 Australian Open women's semifinal odds and released his coveted best bets for Williams vs. Osaka. His picks include a play on the outright winner and advice on how many sets the match will go! You ABSOLUTELY need to see all of Mair's picks and analysis of the 2021 Australian Open before you bet.

So who wins the Williams-Osaka semifinal? And which pick could lead to a huge return? ... Join SportsLine right now to see Gavin Mair's Williams vs. Osaka picks, all from the acclaimed expert who hit it big in the last grand slam women's final! -- Use promo code TENNIS to get your first month of SportsLine for a buck!