Abby WambachThe most dominant player in women's soccer as the World Cup approaches, Wambach fills a role on the soccer field that is not altogether dissimilar to great big men like Shaquille O'Neal and Hakeem Olajuwon on the basketball court. When her team needs a score, they get her the ball, either at her feet or on her head, and let her go to work against smaller opponents swarming, hacking and hoping to slow her down. With her goal against Japan on July 28, Wambach tied Cindy Parlow for fifth all-time among American players with 75 goals and now trails only Mia Hamm, Kristine Lilly, Michelle Akers and Tiffeny Milbrett. Of that quartet, no player scored with greater regularity than Akers, who scored her 105 goals in 136 goals, an average of 0.77 goals per game (Hamm ranks second at 0.57 goals per game). But as Wambach closes in on her 100th cap, a milestone she will reach in China if the United States advances to the quarterfinals, she is averaging 0.80 goals per game. Given the era in which she plays, with an ever-improving level of play around the world, she at least merits a place in the discussion as the best goal scorer in the history of women's soccer. Wambach is physically imposing, and her size and strength unquestionably are a big part of her success, especially in the air where she is essentially impossible to mark with just one defender on set pieces. But size is only part of the equation for a player whose motor never stops and who doesn't get enough credit for her nimbleness and deft touch with the ball at her feet and defenders hanging on her back. Kristine Lilly The most capped player in the history of international soccer, men's or women's, with nearly 330 appearances for the national team, Lilly is by almost all accounts, still at the peak of her abilities at 36 years old (World Cup teammate Stephanie Lopez was born one year before Lilly debuted for the United States in 1987). She finished second in FIFA Player of the Year balloting in 2006 after scoring 13 goals in 20 games and had seven goals in 10 games this year through the end of July. A midfielder for much of her tenure with the national team, including starting roles with every American World Cup entry since the event's inception in 1991, Lilly moved to forward following Mia Hamm's retirement and Greg Ryan's ascension to head coach and flourished in the role. Able to score directly while taking free kicks and lethal on penalty kicks, she is also adept at creating chances during the run of play. While stats aren't available, it seems safe to say no American player puts more shots on goal from inside the 18-yard box. The captain in every game in which she has played in the last three years, Lilly leads largely by example. Lindsay Tarpley The former University of North Carolina star and Hermann Trophy finalist has become a versatile role player for the United States. Tarpley may never develop into the unquestioned offensive star of the national team, but relentless, tireless and without ego, she has emerged as an ideal complement up top alongside Wambach and Lilly. She is adept at working in space with or without the ball, spreading the field and creating room for her running mates, and has a knack for finishing off plays around the goal. Just 23 years old (she'll turn 24 during the World Cup), she is already among the more proven commodities in pressure situations for the United States, having scored in sudden death to give the United States the title in the 2002 U-19 World Championships and against Brazil in the gold-medal match of the 2004 Olympics. Her all-around skills make her a good fit as either an attacking midfielder, as she was in the Olympics, or as a forward. Tarpley's knack for finishing and Ryan's penchant for playing three forwards point to a full-time spot up top in China. Heather O'Reilly Both the youngest of the seven players on World Cup roster with double-digit career goals and one of just three players, along with Wambach and Lilly, to score at least one goal in each of the last six years, O'Reilly remains a mix of experience and potential. She has been the national team's de facto fourth forward since last fall, when she remained at the University of North Carolina for her senior season instead of playing with the national team as it prepared for the Gold Cup. That decision, rewarded with a national championship when she deftly led a young team through the NCAA Tournament, allowed Lindsay Tarpley to solidify her hold on the starting spot opposite Wambach and Lilly that O'Reilly occupied for 11 of the national team's first 13 games last year. Whether O'Reilly starts or comes off the bench, she will be asked to play a significant role in China, just as Shannon MacMillan did in providing instant offense off the bench in 1999 (and as MacMillan struggled to do after making a remarkably swift return from an ACL injury four years later, leaving the United States with little reserve punch). Natasha Kai Kai's inclusion on the final World Cup squad was hardly surprising given her regular appearances during Ryan's residency camps and on game rosters over the last year, but she remains one of the more intriguing names to make the cut. On a team that still occasionally lacks an offensive spark during the run of play, Kai certainly has plenty of incendiary potential when she starts dribbling through traffic or unleashing a canon shot -- the kind of spark that produced six goals in just 702 minutes last year. Of course, she also has enough raw edges at the international level to burn her teammates with ill-advised attacking forays and defensive lapses just as easily as she burns opponents. Ryan's decision may have been made with an eye toward the future, hoping the exposure to a World Cup environment will be the next step in focusing Kai on the demands of a career at this level after playing her college soccer at a middle-tier program like Hawaii. But in passing over college-eligible rising stars like Lauren Cheney, Danesha Adams and Megan Rapinoe, he seems to have left evidence that he wanted his sixth forward to have at least the potential to be more than a spectator in China. Graham Hays is a regular contributor to ESPN.com's soccer coverage. E-mail him at Graham.Hays@espn3.com.