With under five minutes left in the first quarter, Raptors center Marc Gasol recorded a steal and tossed the ball to backup point guard Fred VanVleet in transition. The guard raced down the court with Siakam as Warriors forward Draymond Green defended on the play.
VanVleet lobbed the ball over Green as Siakam timed his jump. The forward leaped and rattled the rim with the one-handed slam.
Siakam, who had 32 points and eight rebounds in the Raptors' Game 1 win, had seven points, three assists and two rebounds in 21 minutes during the opening half. He shot 3-of-8 from the field.
The Raptors led the Warriors 59-54 at halftime. Toronto holds a 1-0 lead in the best-of-seven series.