Logan Nelson and Brandon Fushimi scored for the Royals (4-5-0), who trailed heading into the third period.
Beau McCue scored the lone goal for the Americans (2-5-1), who have dropped back-to-back contests.
In his first-career WHL start, Evan Sarthou made 23 saves in a losing cause.
Both clubs had chances to score in the first period, but the game remained scoreless after 20 minutes of action.
Tri-City dominated the second period at times, outshooting Victoria 17-4, and McCue put the Americans on the board with a power-play goal at 13:25.
Sarthou tried to hold off a Royals' comeback, however Nelson finally put one past him while on the man advantage at 4:31 of the third.
Fushimi then put the Royals ahead with the eventual winner at 11:35.
Victoria scored on its only chance with the man advantage while Tri-City went 1-for-6 on the power play.
Thunderbirds 4 Ice 3
CRANBROOK, B.C., — Danny Mumaugh made 39 saves as Seattle slipped past Kootenay.
Justin Hickman scored the winner for the Thunderbirds late in the third period (5-2-0) while Mitch Elliot, Mathew Barzal and Roberts Lipsbergs scored the others.
Sam Reinhart and Jaedon Descheneau had a goal and an assist apiece for the Ice (3-2-1) and Jon Martin added a single goal.
Wyatt Hofflin stopped 34-of-38 shots in defeat.
Pats 5 Blades 4 (SO)
REGINA, — Boston Leier scored twice in regulation and again in the shootout as the Pats defeated Saskatoon.
Dyson Stevenson scored once and set up two more for Regina (2-5-0) as Chandler Stephenson had a goal and an assist.
Nathan Burns scored all four goals for the Blades (1-5-1) while Nikita Scherbak assisted on three of them.
Dawson MacAuley made 28 saves for the victory. Troy Trombley stopped 27 shots in a losing effort.