Now the 29-year-old Texas native will be fighting hard to stay on top at the Manulife Financial Classic, beginning Thursday at Grey Silo Golf Course in Waterloo.
Lewis reclaimed the LPGA lead from Park with a win last week at the ShopRite LPGA Classic in New Jersey, her second of the season. Park had leapfrogged Lewis in early 2013 when Park won the Kraft Nabisco Championship before the Tour took a week off.
Lewis admitted that she's had a pretty hectic week so far, not arriving into Canada until Monday.
"It's been a pretty cool week; a pretty whirlwind couple of days," she said. "It's was nice to get the win last week and getting the number one was just a bonus."
Lewis, who has already finished in the top 10 in 10 tournaments this season, has to like her chances heading into Waterloo, where she has tied for fifth and sixth the previous two years.
"I've come here the last few years and played really well," she said.
"I think it's a golf course you have to make a ton of birdies on and I led the tour in birdies last year, and I think I'm leading that stat this year, so I think that fits my game. You have to go out there and attack, and make as many birdies as you can.
"This golf course's length is always an advantage, the par 5s are reachable and I think this year it will be even more of an advantage with the course playing a little bit softer. I'd love to get another win, but at the same time, I just have to keep putting myself there and on Sunday, hopefully, the cards fall your way."
The trick, she said, is not becoming too complacent and preparing the same way as she would for any other tournament, even though Park and No. 1 hopeful Lydia Ko are both at Grey Silo.
"I feel like over the last year I've put myself in position to win so many times that I'm very comfortable," Lewis said. "Sunday last week, the nerves were there initially, but once we got going, I felt like if I took care of my game there was no way anybody was going to beat me."
Someone else Lewis will have to watch for is returning champion Hee Young Park. The South Korean won the Manulife Financial Classic in dramatic fashion last year, beating Angela Stanford in a three-hole playoff. Stanford and Park both shot 26-under 258 at the tournament tying an LPGA record for lowest number of strokes at a four-day event.
Park, ranked 23rd in the world, said she was eager to get back to familiar surroundings.
"Actually this golf course is in perfect shape, everything, and I know how I was feeling and green conditions pretty much perfect, so easy to get used to it," she said. "(Earlier in the week there) was rain here so it got softer, so I can hit more aggressive, which is good."
Park added that she's ready to defend her title, despite suffering a wrist injury "a few months ago". She said after some rest, the wrist feels fine.
"It feels a lot better and I'm back to pretty much normal, I can play," she said. "(The) last few weeks I played pretty good, so I think it's ready."
Lewis is hoping that the wind, which has whipped up the past few days, sticks around for the weekend on the links-style course. She feels that will keep scores down and her in contention.
"I would much rather play a golf course when it's playing hard than when it's playing easy," she said. "What's surprised me the last two years is that I have played well here, because I don't like courses that are just a straight birdie fest and you go crazy. I like it when it's hard and you have to golf shots and things like that.
"The wind this year, I'm actually pretty excited about. I'm excited that it's going to play longer and not as short as in years passed. That gets me excited, I don't know about the other players."
Besides the top three golfers in the world, there are seven Canadians in the field this year — Erica Rivard of Tecumseh, Ont., Nicole Vandermade of Brantford, Ont., Brooke Henderson of Smiths Falls, Ont., Sue Kim of Langley, B.C., Toronto's Rebecca Lee-Betham, Hamilton's Alena Sharp and Jennifer Kirby of Paris, Ont.
Note to readers: This is a corrected story. A previous version had Park tying an LPGA record at the last Manulife Classic with a score of 26 under. She actually tied the record for the fewest number of strokes at 258.