Former No. 1-ranked women’s tennis player Martina Hingis willplay in the Mercury Insurance Open pro-am, which is 9 a.m.-noon onAug. 1 at Rancho Valencia Resort in Rancho Santa Fe, tournamentofficials announced Wednesday morning. Hingis won the Australian Open singles title three straightyears from 1997-99 and Wimbledon and U.S. Open singleschampionships in 1997. She also captured nine Grand Slam doublestitles and in 1998 became the fourth woman in history to complete acalendar-year Grand Slam in doubles. On March 31, 1997, Hingis became the youngest player to achievethe No. 1 ranking at 16 years, 6 months. She is one of five playersto hold the No. 1 ranking in singles and doublessimultaneously. Hingis is a former two-time tournament singles champion at LaCosta, winning in 1997 and ’99. Hingis also teamed with ArantxaSanchez-Vicario to win the doubles championship at La Costa in’97. The public is invited to watch the pro-am and admittance isfree. The 2011 Mercury Insurance Open is July 30-Aug. 7 at the LaCosta Resort and Spa. The field includes two-time defending U.S.Open champion and reigning Australian Open champion Kim Clijsters,former world No. 1 Ana Ivanovic and Rancho Santa Fe’s CocoVandeweghe. Tickets, which range from $10-$125, are available atmercuryinsuranceopen.com or ticketmaster.com.