(Reuters) - American Austin Ernst moved one step closer to her second LPGA title with three birdies in her last six holes to seize a one-stroke lead after the third round of the Lorena Ochoa Invitational in Mexico City on Saturday. The 24-year-old Ernst, who clinched her maiden victory on the circuit with a playoff win over South Korea's Kim In-kyung at the 2014 Portland Classic, carded a flawless five-under-par 67 for a 10-under total of 206. Second-round leader Sarah Jane Smith of Australia slipped back with a level-par 72 at Club de Golf Mexico to end the day in a tie for second with Spaniard Carlota Ciganda (68). More...