Seattle Sounders head coach Sigi Schmid sounded hopeful when asked about Rosales' availability, but also said that it was pretty much a game-time decision when I asked him about it following Wednesday's training session that immediately preceded the team boarding their flight.
On a more positive note, it did look as if Eddie Johnson was able to fully participate in training and seems to be on pace to at least make an appearance in Thursday's Western Conference semifinal.
At the same time, it appears that RSL is dealing with similar kinds of issues. Forward Fabian Espindola was forced to leave Leg 1 at halftime, while Jamison Olave was limited to just 30 minutes in a substitue role. Considering this game could very well go 120 minutes, it would seem unlikely that both would start. Similarly, it seems unlikely both Johnson and Rosales would start.