Jansen (1-0) gave up a run on two hits while striking out two in an inning of relief to record the win in Monday's 4-3 victory over the Reds.
It looked like the Dodgers' closer was headed for his first loss after Matt Kemp singled with Curt Casali at third base, but Joc Pederson's walkoff blast in the bottom of the ninth flipped the script. Jansen now has a 2.45 ERA and 10:2 K:BB through seven appearances, and he's converted all four of his save chances.