Groundbreaking.

That's how MLS and USL-Pro league officials characterized their new partnership during a media conference call on Thursday, when they explained details of the relationship that "has the ability to profoundly and potentially forever change soccer in this country."

"If MLS is going to be everything we want it to be and believe it can be in 10 years, it’s critically important we have a successful lower division in this country," said MLS executive vice president of competition and player relations Todd Durbin. "That’s absolutely critical to the growth of the game. … It’s the strategic importance that this partnership represents in helping us achieve our long-term goal of being one of the best leagues in the world."

READ: MLS and USL-Pro reach deal on restructured lower division

MLS operated a self-contained Reserve League in recent seasons, but league owners voted in November to give MLS clubs three options for reserve player development moving forward: 1) create an affiliation with an existing USL Pro team; 2) join the USL Pro with a standalone team; or 3) continue to participate in the MLS Reserve League while integrating matches against USL Pro teams.

Durbin indicated that the decisions made by MLS clubs over the next couple of years will help determine the ideal long-term model. But he was also adamant that MLS is committed to "building this lower division over the next five, 10 and 20 years."

"Our belief is that by forming this partnership and moving forward, that in very short order all of our teams will either have affiliates or be participationg in interleague play with USL Pro," he said.

It was also confirmed on Thursday that Chivas USA will be the only MLS club that will not have a USL affiliate partnership or play matches against USL opposition in 2013. Durbin expects the Goats to be involved in upcoming seasons.

LISTEN: March to the Match breaks down the Reserve League news

As far as Canada is concerned, USL president Tim Holt said that USL Pro would seek to engage the Canadian Soccer Association regarding the status of potential new clubs in Canada, despite comments by the CSA's president vowing not to sanction USL Pro as a third-division league in Canada.

There was also little concern that the new relationship between USL Pro and MLS would have a competitive impact on the Lamar Hunt US Open Cup, which sees frequent meetings between clubs from the two leagues.

"The players will be cup-tied and they’re going to play for the team they participate with," Durbin said. "It could end up being a phenomenal rivalry as to which [club] is going to win the game. My expectation is that when the players are on the field, that everyone does everything in their power to win the game."

Whatever challenges do arise as the two leagues embark on this new relationship, it was clear that there's a commitment from both sides to make the new relationship work with the best interests of American soccer in mind.

"Our goal in all of this is to help build a league that is competitive and that is compelling," Durbin said. "And if we achieve that and continue the growth of USL Pro, which has made great strides over the past few years, that the end result of that will be better players, better front office staff, better referees, better administrators and better coaches."