Shahar Pe’er suffered a humbling exit from the Sony Ericsson Open in Miami on Sunday.The 22-year-old, ranked No. 20 in the world, claimed just one game in a 6-0, 6-1 third-round defeat to Kim Clijsters (16), lasting only 50 minutes against the Belgian mother, who came out of retirement last year.Pe’er struggled on serve and on return. She won a mere 2-of-23 points when Clijsters hit her first serve in, while taking just 4-of-22 points on her second serve.Elsewhere, unseeded American Mardy Fish earned one of the biggest victories in his 10-year career Saturday with a 6-4, 6-4 upset win over 2009 champion Andy Murray.Murray, the Australian Open runner-up in January, was seeded No. 3 at Key Biscayne but failed to survive his opening match.“He probably didn’t play the way he did in Australia,” Fish said. “But I don’t care.” Murray confirmed he has been struggling the past two months and described the problem as mostly mental. “It’spurely down to me, what goes on inside my head,” he said. “It doesn’tmatter how well you practice. You need to be tough in the matches.” Top-ranked Roger Federer held every service game and won his opening match by beating lucky loser Nicolas Lapentti 6-3, 6-3. Federer,the Key Biscayne champion in 2005-06, has an inviting path to the finalwith Murray out. No. 2 Novak Djokovic was eliminated Friday.