The United States Soccer Federation has tweaked its format for this year's Lamar Hunt U.S. Open Cup, the nation's oldest soccer tournament, which pits teams from every level of professional American soccer against one another.

The changes for this year's 99th edition of the Open Cup will benefit the Carolina RailHawks and other North American Soccer League teams.

The NASL was not allowed to play in last year's Open Cup due to its ongoing struggle to get USSF sanctioning.

Not only will the RailHawks and other NASL teams be part of this year's tournament, which has expanded to 64 teams, but there is a greater likelihood that Carolina will host a team from Major League Soccer.

Unlike years past, where teams had to place a silent bid to host any particular round - with the team with the bigger check winning the round - there is no cost this year for hosting a first or second-round game and a flat fee for any round beyond that - so long as the team has a venue that meets USSF standards. If both teams place a bid to host a round, then a blind draw will determine the host.

MLS teams had an advantage in previous Open Cups of being able to bid more than the lower-division franchises, and almost always hosted those head-to-head games. The bids often had to be submitted almost a week before the next round, so teams did not know which opponent they would be facing.

Sixteen teams from MLS, six from NASL, 10 from USL PRO and 32 amateur club teams will make this year's field.

The amateur club teams must qualify for the tournament before playing each other in the first round May 15. The NASL and USL PRO teams join the fray in the second round May 22, while MLS teams enter the tournament May 29 for the third round.

After the third round, the Open Cup will take a three-week break and resume June 26 with the quarterfinals. The semifinals are slated for July 10 and the Open Cup Final will be either Aug. 7 or 8.

There is prize money for the most successful teams. The winner takes home $100,000, the runner-up receives $50,000 and the three teams that advance the farthest among Division 2, Division 3 and amateur clubs will be awarded $10,000 each.

The RailHawks have not been strong in Open Cup play since 2007, when Carolina advanced to the semifinals, but new coach Colin Clarke has a track record of faring well in similar tournaments.

In the CONCACAF Champions League, a tournament among professional teams in the Caribbean as well as North and Central America, Clarke's Puerto Rico Islanders advanced to the group stage in 2010.