SEATTLE — After a lackluster first half in which the Seattle Sounders dominated possession but had precious few genuine scoring opportunities, a 47th minute goal from Will Bruin flipped the game on its head. That forced Santa Tecla out of its bunker and eventually to their downfall. The Sounders scored three goals between 69’ and 83’ to put the match away, beating Santa Tecla 4-0 (5-2 on aggregate) to advance to the CONCACAF Champions League quarterfinals against Mexican giants Chivas (they’ll host them on March 7). The capper was supplied by debutante Mangus Wolff Eikrem, finishing a beautiful give-and-go with Clint Dempsey that should have Sounders fans salivating.