After going six shots ahead of the field at the Women's British Open on Saturday, the top-ranked Mexican can at last see the finishing line for her first major victory in her 24th attempt.
Ochoa shot a second straight par 73 and was the only player under par on the Old Course at St. Andrews. She is at 6-under 213, six shots ahead of Linda Wessberg of Sweden (72).
The biggest danger may come from Annika Sorenstam (77), one of four players seven shots back at 1-over 220.
'I'm not going to pay attention to other players and just play my own game and try to be aggressive and make some birdies,' Ochoa said. 'I think once you try to start doing something different you get in trouble. I just want to play my game and hopefully, I can win maybe by more.'
Ochoa is lithely built but physically strong, something she attributes to marathons. She ran a half-marathon in her home city of Guadalajara, and a marathon at Tucson when she was studying at the University of Arizona.
'I like to train for half-marathons,' she said. 'Even on the tour, I like to think we are running in a marathon and we are just training. You can go really, really far. It helps me to know just how far I can go and never to give up, and just keep on going and be tough.
'In a way you can relate it to golf. Just always be strong and have a mind-set that you can do it and that you want to make it.'
After twice finishing second in majors -- as well as coming third and fourth -- this may be the first time she crosses the line first.
With winds gusting up to 35 mph at the home of golf, virtually all of Ochoa's rivals dropped shots. The only three sub-par rounds of the day came from golfers way back in the field who played in the calmer part of the day.
One of those was Wessberg. She was tied for 19th at the start of her round, but recorded her fourth birdie of the day at the 18th to compensate for a double-bogey 6 at the 13th.
Sorenstam bogeyed four holes on the outward nine but made a good recovery.
'I was just trying to be smart, hit fairways and greens and go from there,' Sorenstam said. 'I believe I shot level-par the last 10 or 11 holes. I'll take that any time in a championship like this. I just didn't get off to a good start.'
Ochoa punctuated her solid round with some spectacular play.
She sank a 30-foot birdie putt at the third and just missed a 60-foot eagle at the fifth. The ball rolled up one slope and down another to creep past the rim of the cup and leave her a 1-foot birdie.
She also benefited from a two-shot swing at the 12th, where she holed a 2-foot birdie putt and playing partner Wendy Ward missed a 7-foot putt for bogey.
Starting one shot behind and tied for second, Ward had six bogeys and a double-bogey 7 at the 17th, where she needed four shots to reach the green. She finished with an 80 for a share of seventh at 2-over 221.
While most players were shooting high 70s or into the 80s in the strong wind, Stacy Prammanasudh shot a 1-under 72. The American had three birdies and moved up from 52nd to a tie for 12th at 3-over 222.
Juli Inkster has had three wildly erratic rounds. The seven-time major winner threatened for the lead during a second-round 68, which was an 11-shot improvement on her opening 79. Her third-round 82 was a 14-stroke swing the other way as she finished tied for 51st at 10-over 229.
Lotta Wahlin of Sweden justified her decision to walk off the course in near darkness after 16 holes on Friday and continue her round just after dawn on Saturday. She birdied the 17th and finished at 5 under to just make the cut. After a short break, she was back on the first tee and finished at 78 for a 229.