This match turns on the quality of the first pass into the box after each side wins the ball. Adelaide have shown several ways to create that pass, from wide combinations to a direct ball through midfield. Pathum can answer quickly through Andersen or Belmonte finding Gustavsson, so the second ball matters as much as possession.
Adelaide's win over Tai Po showed the shape of their attack. Yull released Barnett for a cutback to Alagich, Kikianis played Muñiz through the middle, and Goodwin combined with Talladira on the left. Those are distinct ways to test Pathum's midfield cover and the Nikolić-Osmanović defensive line.
Pathum's attack still has useful outlets: Gustavsson scored against Ayutthaya, Belmonte supplied crosses, and João Magno made an impact from the bench. Chanathip, whose pass created their equaliser against Lion City, did not play against Ayutthaya and was reported unavailable for this match. Goodwin has travelled with Adelaide and spoken from Bangkok after scoring against Tai Po.
I expect Adelaide to seek both flanks and the pass behind Pathum's midfield, then work to recover the first clearance. Pathum will look for Gustavsson quickly when they regain it. Adelaide's variety of box entries against Pathum's changed central connection is why I'm siding with Adelaide United to win this match.