MIAMI - Australian Matthew Ebden will be the first opponent for defending ATP Miami Masters champion Andy Murray after the Scotsman revealed his shock split with coach Ivan Lendl on Wednesday. Ebden, ranked 67th, booked his Friday match against the reigning Wimbledon champion by defeating Poland's Lukasz Kubot 4-6, 6-4, 6-4 as men began play Wednesday at the ATP and WTA hardcourt event.Murray beat Ebden in their only previous match, a Shanghai quarter-final three years ago. The post-Lendl test comes in the wake of Murray's announcement that he has called it quits with his Czech-born coach after a two-year partnership. "I'm eternally grateful to Ivan for all his hard work over the past two years, the most successful of my career so far," Murray said. "I'll take some time with the team to consider the next steps and how we progress from here."Under Lendl's guidance, Murray won a 2012 London Olympic gold medal, the 2012 US Open and last year's Wimbledon title. "Working with Andy over the last two years has been a fantastic experience for me", Lendl said. "He is a first class guy. Having helped him achieve his goal of winning major titles, I feel like it is time for me to concentrate on some of my own projects moving forward including playing more events around the world which I am really enjoying." Argentine eighth seed Juan Martin del Potro withdrew from Miami on Wednesday, still suffering badly with the left wrist injury which has compromised his season. "I still feel pain in my left wrist and I don't feel competitive to go on court," Del Potro said. "It's a pity because this is a special tournament for me since there are many Latin fans and Argentines in particular. In the next few days I will visit my doctor again to determine the following steps."German lucky loser Benjamin Becker replaced del Potro in the draw, which has all seeds given byes into the second round. Del Potro has been troubled by the wrist since injuring it in his opening match at the Australian Open three days after winning the Sydney title in early January. The former US Open champion has tried to play but with little success, winning one round at Melbourne and reaching a Rotterdam quarter-final before retiring in the first round of Dubai against India's Somdev Devverman. In opening men's play, Adrian Mannarino of France beat Russian veteran Nikolay Davydenko, the 2008 champion, 6-4, 7-5. The French pair of Jeremy Chardy and Julien Benneteau advanced, with Chardy needing more than two and a half hours to beat Argentine Juan Monaco 7-5, 3-6, 7-6 (7/5) and Benneteau stopping British wild card Kyle Edmund 6-7 (2/7), 6-3, 6-2.In a WTA field led by defending champion Serena Williams, China's Peng Shuai defeated Czech Karolina Pliskova 7-5, 6-0. American Vania King blanked Spaniard Estrella Cabeza Candela 6-0, 6-0 while Swede Rebecca Peterson eliminated Germany's Mona Barthel who retired with a stomach complaint while trailing, 6-4, 4-2. American Lauren Davis, who reached the fourth round last week in Indian Wells, advanced over China's Zhang Shuai 6-2, 6-3. Croatian Donna Vekic, 17, beat Japan's 43-year-old Kimiko Date-Kurmm 7-6 (7/2), 6-2 with the evergreen Asian veteran reaching the Miami final in 1995 -- 15 months before her opponent was even born. Russian Nadia Petrova defeated Ursula Radwanska 7-5, 1-6, 6-4, US qualifier Coco Vandeweghe defeated Marina Erakovic of New Zealand 6-4, 7-6 (8/6) while American Christine McHale beat China's Zheng Jie 6-4, 6-2.