Hours after Lee completed her morning round, the top-ranked Ochoa birdied five of her final eight holes for a 5-under 67 and a share of the second-round lead with Lee.
Ochoa and Lee (69) had 9-under 135 totals. Jane Park (68) was two strokes back, and Juli Inkster (68), Brittany Lincicome (71), Sherri Steinhauer (69) and Young Jo (67) followed at 5 under.
Ochoa, who won the Sybase last year when it was played at Wykagl Country Club in New Rochelle, N.Y., hasn't won since taking over the No. 1 ranking from Annika Sorenstam last month, though she has two top-five finishes in three tournaments.
On Friday, the Mexican star corrected a putting glitch on the front nine and sailed through the back nine in 5 under.
'I started a little bit off, but it turned out to be a good day,' Ochoa said. 'I think I was a little bit close to the ball, just a little uncomfortable there, so I had to make sure I kept a little more room on the back and swung a little bit easier.'
Ochoa would have grabbed the lead at the end of the day if not for a missed 5-foot birdie putt on No. 16, a 365-yard par 4. She started to pick up her play with birdies on Nos. 11 and 12, which came after a front nine in which she'd alternated birdies and bogeys. She was able to carry the momentum through the rest of her round.
The birdie on 12 was significant because she made a double bogey the hole Thursday.
'As soon as I made the birdie on No. 11, I wanted to make sure we just got a good rhythm, and making birdie just gave us a better feeling for the rest of the holes,' she said.
Conditions were a major variable Friday, particularly for players who teed off in the morning. Weather forecasts had called for rain and cold, and though the course stayed dry throughout the day, temperatures had barely reached the low 50s when the first threesomes went out into a persistent wind. Lee and others wore headbands to keep their ears warm, and Nina Reis even wore a wool hat and gloves.
'It was cold out there,' Lee said. 'I took an extra 20 minutes to warm up and my body still wasn't moving very well. But usually the weakest part of my game is playing in cold weather, so I'm pretty satisfied.'
As most of the gallery trailed after the threesomes featuring Ochoa and other higher-profile players when they teed off just after noon, Lee was quietly finishing her round to temporarily maintain her first-round lead.
Like Ochoa, Lee's big breakthrough came midway through her final nine holes. On No. 5, a 470-yard par 5, she hit a 4-iron onto the green and sank a 54-foot putt for eagle. Two holes later, she birdied No. 7 with a 27-foot uphill putt.
The birdie put her at 10 under, and she saved par on No. 8 with a sand wedge to 4 feet. She gave one stroke back on the par-4 ninth when she hooked her drive into the left rough and wound up missing a 15-foot putt for par.
Park turned professional last year after playing a year at UCLA and admitted she is unaccustomed to being near the top of a leaderboard after two rounds. She said she made a point not to check the scoreboard for other players' scores.
After a double bogey on No. 10, Park rebounded with an eagle on 11 and made three more birdies to finish 4 under for the day and 7 under for the tournament. Now, she comes face to face with Ochoa.
'It's motivating, and it's humbling too,' Park said. 'It's great to be in the same field with her and competing against her and all the other players. It's an honor, really.'
Jo tied Ochoa for the day's best round with a 67 on the strength of three birdies on each nine and a bogey on No. 9, a 420-yard par 4 that also was bogeyed by Lee, Ochoa and Pak.
Steinhauer began the day at 2 under and had just bogeyed No. 12 to drop back to 1 under when she saw Lee move to 10 under.
'I started thinking, 'Ugh, that's a long way off,'' Steinhauer said. 'At that point I just said, 'I can't worry about what she's doing' and just kept concentrating on my own game.'
The veteran found her groove midway through her round and had five birdies in a span of eight holes, culminated by a sand wedge to 3 feet on par-5 seventh.