MIAMI - Huge crowds have swarmed to matches across the United States in recent weeks but Major League Soccer will not abandon its gradualist approach to developing the game, according to MLS commissioner Don Garber. He told Reuters while the boom in interest is unprecedented it will take time for the 13-year-old league to expand, become more profitable and loosen up its regulations on salaries. Garber celebrates his tenth year in charge of MLS in the midst of a 'Summer of Soccer' which has seen massive attendances at international friendlies such as Wednesday's meeting between the Seattle Sounders and European champions Barcelona. "When I first took this job, I thought it might be just about turning the lights on and all of a sudden soccer would get in a position to explode," Garber said in an interview. "Over the last decade I've realised there is tremendous potential for this sport but still enormous challenges. "But I don't believe even in 1999 that I expected that the sport would be as popular as it is today. The games that have taken place over the last few weeks of this summer, I think, are almost unprecedented in American sport. "We had 93,000 on Saturday night at the Rose Bowl (in Pasadena) for LA Galaxy against Barcelona which is the largest crowd in the United States since the 1994 World Cup. In many ways the sport has grown in ways I never believed it could. LONG TIME "But we do recognise that for MLS to benefit from the popularity of the sport we really need to work hard at converting all of these soccer fans into being very committed MLS fans -- that is a process that is ongoing and I think will continue to take a long time," he added. One of the problems facing MLS is that most of the leading American players have left the league for more lucrative deals and tougher challenges in the European leagues - a trend that does not worry Garber unduly. "Clearly, you want a league where the best players in America can play," said Garber. "Currently the best player in the country, Landon Donovan, is in the league. But we have to educate the fan base that players leave leagues all the time. "The Argentine league is consistently selling players to Europe but people are still fans of River Plate and Boca Juniors, so we have got to get to the point where the sports world understands that dynamic. "But we have also to arrive at the point where we can have the kind of league that can afford to keep the players we want to keep and have the kind of environment that will help them develop. Again that's something I think will work in time." Garber is wary - for the moment - of salary cap rises to keep players in the MLS and of expanding the league. STRONG POSITION There are now 15 teams with Philadelphia Union joining next year to be followed by Portland and Vancouver in 2011. The MLS chief says Montreal is in a "very strong position" to become the 19th team and envisages a 20th team in the future before a period of consolidation. That 20th team could come from Florida or Georgia as the league looks to gain a presence in the south-east. "We need a team south of DC. Where that is and when that comes we don't know today but I've always said it is a 'when' not an 'if'. I don't know when that 'when' is though," he said. Garber believes the blueprint for new teams is clearly to follow the path of the Seattle Sounders, who entered the league this season and are averaging home crowds of 30,000. "We have a perfect storm (in Seattle) of very passionate fans, deeply committed MLS fans. The Sounders matter in this market, they are very relevant and more relevant than any international club (is to fans in Seattle). "It is part of the process of working hard on that conversion, having the right brand, having the right facility and the right players on the field. "Certainly we want to learn from the success and have the owner, general manager and marketing manager working with some of our other teams to give them the blueprint to success," he said.