After spending two "great" weeks together in the United States, McIlroy believes he and the 21-year-old from Denmark can be good for each other's careers.
"I think we definitely spur each other on. She's number one in the world and I've got a major, and we sort of both want what each other have," the sixth-ranked McIlroy said Wednesday before the European Masters. "It's a big goal of mine. I want to become the best player in the world."
McIlroy is playing his first tournament since injuring his right arm at the PGA Championship three weeks ago. While recuperating, the 22-year-old Northern Irishman accompanied Wozniacki to tournaments in Cincinnati and New Haven. She is bidding for a first Grand Slam title at the U.S. Open, which began this week.
McIlroy said he was impressed with Wozniacki's dedication and picked up pointers on improving his game.
"She's got a great work ethic and it's something I can probably learn a lot from. It's a lot more physically demanding than golf," said McIlroy, adding he's a longtime tennis fan. "They do put the work in, they really do. It's just amazing how they can get up each morning and keep doing the same thing, putting their bodies through that. It's pretty impressive."
McIlroy said the couple is "taking a day at a time," knowing tournament schedules leave few chances to meet this year.
He watched on television Tuesday night when his top-seeded girlfriend opened at Flushing Meadows with a 6-3, 6-1 win over Spain's Nuria Llagostera-Vives.
Wozniacki is scheduled to play Thursday, after McIlroy completes his first round at the European Masters. It counts as the first points-scoring event toward representing Europe in the 2012 Ryder Cup.
McIlroy's goal is chasing No. 1 Luke Donald of England, who plays in the United States this weekend.
"I don't think it's achievable in the short term, Luke is quite a long way ahead," McIlroy said.
He calculates he can rise to a career-high No. 3 with victory at the Crans-sur-Sierre club, and if other results fall his way. Fifth-ranked Martin Kaymer of Germany is in the European field, while Americans occupying third and fourth spots -- Steve Stricker and Dustin Johnson -- play at the Deutsche Bank Championship in Boston.
McIlroy will look for inspiration from "one of the most beautiful places in the world," where he almost got his first professional win as a 19-year-old. He took a four-stroke lead into the final round in the Swiss Alps but lost in extra holes to Frenchman Jean-Francois Lucquin.
"I still think about that playoff in 2008," said McIlroy, who has yet to win in Europe as a pro. His sole European Tour victory was at Dubai in February 2009.
McIlroy said his injured right arm is less of a factor. He was injured after hitting his club on a tree root just three holes into his PGA challenge. The damage spread from his wrist to shoulder as he compensated for the pain.
"Now it's not painful. It's more like a numb sensation, like if someone gives you a dead arm," he said after a morning practice Wednesday. "It's nearly 100 percent and I'm happy with it."
As the only tournament in Europe sanctioned by both the European and Asian Tours, 30 players will participate from the other circuit, including money leader Noh Seung-yul of South Korea.