Atlanta United has always believed they could win. Here's why they pulled off the greatest upset in the history of the MLS Cup Playoffs.

Inter Miami welcomes Atlanta United FC to Chase Stadium Saturday for the finale of their best-of-3 first-round playoff series. Kickoff is set for 8 p.m. ET (Apple TV). Let's analyze BetMGM Sportsbook'

Inter Miami has played Atlanta five times this year, and won just once, 2-1 in the playoff opener at home. Atlanta beat Miami 3-1 back in May, they tied 2-2 in September, and Atlanta stunned Miami on Saturday to force Game 3 with an extra-time game winner by Xande Silva before a crowd of 68,455 at Mercedes-Benz Stadium.

FORT LAUDERDALE, Fla. — Lionel Messi and Inter Miami were eliminated in the opening round of the MLS Cup Playoffs in a stunning upset, losing 3-2 at home to ninth-seeded Atlanta United on Saturday at Chase Stadium.

BOTTOM LINE: Atlanta United hosts Inter Miami in the Eastern Conference finals. United is 11-10-7 against Eastern Conference opponents. United ranks third in the Eastern Conference drawing 187 corner kicks, averaging 5.5 per game.

D espite winning the Supporters' Shield and setting a new record for points in a season with 74, Inter Miami are on the brink of being eliminated in the first round of the playoff

Bartosz Slisz scored on a 76th-minute header and visiting Atlanta United completed one of the biggest upsets in MLS Cup Playoff history with a 3-2 win over Lionel Messi's Inter

Lionel Messi and Inter Miami may have won the Supporters' Shield, but their regular season title means nothing as they were shocked by ninth-seeded Atlanta United at home to bring their season to an inauspicious end.