$ 0 0 Fifth-seeded Juan Martin del Potro has been eliminated from the AustralianOpen in the biggest upset of the tournament this week, beaten 4-6, 6-3, 5-7, 6-4, 7-5 by Roberto Bautista Agut of Spain. It was Bautista Agut's first win in seven matches against a top 10 player, and del Potro's fourth second-round exit in eight years at the season's first major. The match lasted 3 hours and 53 minutes and ended at 1:20 a.m. Friday after a long day of match suspensions and delays due to extreme heat and storms."I think he played a great match over nearly four hours," del Potro said. "But in every (important) moment ... he played an unbelievable shot. In break-point down, he served well. He made winners with forehands, backhands, and he played always down the line very often." Bautista Agut had only ever played two five-set matches, losing both, and is now into the third round of a Grand Slam tournament for the first time. Del Potro won his 18th career singles title last week by beating Bernard Tomic in the final of the Sydney International, a key warm-up event for the AustralianOpen, and was considered the leading contender from outside the "Big Four" for the Australian title.