The choice of Atlanta for an MLS expansion team makes sense, as it's the ninth-largest metropolitan area in the U.S. by population. (Pouya Dianat/Atlanta Braves/Getty Images)

Atlanta has emerged as a prohibitive favorite to host an MLS expansion team, SI.com has learned.

Multiple sources have confirmed that the league and Atlanta Falcons owner Arthur Blank are deep into discussions that likely would result in an MLS club sharing a downtown stadium with the NFL franchise. The Falcons intend to open a new $1 billion, retractable roof facility in 2017 adjacent to the Georgia World Congress Center, which is just north of the Georgia Dome.

It’s unclear whether Blank’s MLS team would launch in 2017 or join the league earlier and play in a temporary home. The new stadium is being designed with a wide, soccer-friendly field and MLS locker rooms. It also may feature a secondary retractable roof system that will cover the upper tiers, leaving approximately 27,000 seats available for league games. The Vancouver Whitecaps use a similar configuration at BC Place.

On Thursday afternoon, The Atlanta Journal-Constitution reported that negotiations between Blank and the league “accelerated” when the Falcons received approval for the new stadium, which will be 70-80 percent privately financed. Opening the new facility with an MLS game has been discussed, according to the AJC.

SI.com spoke to three sources with knowledge of Atlanta’s expansion effort following the release of the AJC article.

MLS commissioner Don Garber announced in late July that the league plans to field 24 teams by 2020. There currently are 19. New York City FC, a joint venture between England’s Manchester City and the New York Yankees, is scheduled to begin play in 2015.

SI.com understands that Garber told MLS staffers during meetings in Columbus this week that three of the four subsequent expansion sites (after NYCFC) already have been decided. He used similar words when speaking to Canada’s TSN on Wednesday.

Orlando City, a USL Pro (third tier) club that claimed its second championship in three years on Saturday before nearly 21,000 fans at the Citrus Bowl, appears destined for MLS. Assuming an October vote on using an existing tourism tax to fund the final quarter of the club’s $80 million downtown stadium project goes well, MLS should be ready to announce Orlando’s addition by the end of the year. The Lions could take the field as an MLS team as early as 2015.

The second of the three cities to which Garber referred to is Miami, although its progress isn’t as clear-cut as either Orlando’s or Atlanta’s. Former L.A. Galaxy midfielder David Beckham, who holds an option to purchase an MLS expansion team, has been focusing on Miami. He has been working with Marcelo Claure, a Bolivian billionaire who went to college in Massachusetts and made his fortune in the wireless industry.

On Wednesday, Miami Dolphins owner Steve Ross told attendees at the Bloomberg Sports Business Summit in New York that he was interested in bringing an MLS club to South Florida. A source told SI.com that Beckham and Ross are not currently working together. Ross has been trying to get public funding to help pay for a renovation of Sun Life Stadium.

In comparison, Atlanta appears to have its house in order. It is the ninth-largest metropolitan area in the U.S. by population, a massive transportation hub and it would serve as a natural rival for either Orlando, Miami or both. The Atlanta Silverbacks of the second-division NASL play at a 7,500-seat facility located about 15 miles northeast of the Georgia Dome. The last top tier team to call the area home was the Atlanta Chiefs. The old NASL club existed in two incarnations, the latter folding in 1981.