Webb turned professional two months before her twentieth birthday and then spent a year playing professional golf in Europe and on the Futures Tour in the United States. In 1995 she won the Weetabix Women's British Open while still on the Women Professional Golfers' European Tour. That year Webb qualified for the LPGA Tour, on her first try, by finishing second at the LPGA qualifying tournament despite playing with a broken wrist.
The next year Webb took the golf world by storm. She won the Health South Inaugural, only the second tournament she competed in as a member of the LPGA Tour, and then went on to win three other events that season. She set an earnings record by becoming the first female player ever to win more than $1 million in a season, and she was also the only rookie, male or female, to make over $1 million in his or her first season.
Not long after Webb joined the LPGA Tour, a rivalry of sorts developed between her and the then-current champion, Sorenstam. It is not a particularly acrimonious rivalry, but the two young women find themselves battling each other for wins and for first place in the statistics more often than they find themselves battling any other single golfer. Not since 1994 has a golfer not named Webb or Sorenstam won the Vare Trophy for lowest scoring average, for example, and when Webb won an astounding seven tournaments in 2000, Sorenstam came roaring back to win eight in 2001.
In 1999 Webb got her first victory in a major tournament, the du Maurier Classic, and set an LPGA scoring average record with 69.43. Then, in 2000, Webb won the first four tournaments she entered. She added only three more wins in the rest of the season (partially because she took some time off to return to Australia and run with the Olympic torch before the Sydney Olympics), but two of those wins were at majors: the Nabisco Championship and the U.S. Women's Open. That year Webb also won her second consecutive player of the year award and Vare Trophy. Throughout the year, comparisons between Webb and Professional Golfers' Association star Tiger Woods were ubiquitous. Fans of women's golf saw sexism in the fact that Woods's achievements received so much more attention from the media than Webb's did, and several even suggested that the two compete head-to-head to prove that Webb was just as good a golfer as Woods.
Early in the 2001 season, Sorenstam seemed to be emerging as the dominant player and Webb seemed to be fading. Webb was still playing excellent golf—for the second consecutive year she made every single cut, and she usually finished in the top—but she just could not seem to win. Then, in June, Webb ran away from the rest of the field at the U.S. Women's Open to win by eight strokes. Not since 1980 had someone won that event by that large of a margin.