The sharp single was cleanly handled by Panthers center fielder Davey Feess, who rocketed a strong throw to the plate.
While Feess' throw beat Selsor, the toss was dropped at the plate as Selsor slid home.
Georgino's hit was also notable given that the Spartans finished one for 12 with runners in scoring position with two runs batted in.
Georgino helped led the Spartans' rally from a two-run deficit when he smacked a solo homer off the roof in the fourth inning against Panthers starting pitcher David Orndorff (0-1) to knot the game at 2.
La Cañada's first run came in the third inning after second baseman Jacob Yonan walked to lead off the inning and then took second on a throwing error from Orndorff, who overthrew a pickoff attempt at first base.
Matteus de Faria advanced Yonan to third on a bunt and Clayton Herrmann scored the second baseman with an RBI grounder to short.
The Spartans (5-3) began the game in a rocky fashion, surrendering solo runs in the first and second innings.
Poly (2-3) scored in the first inning on a two-base error in right field that allowed Logan Beerman to reach second to begin the frame and eventually come home on an RBI grounder from Jonah Campbell.
In the second inning, Orndorff singled to begin the inning and advanced to third on a two-base throwing error from Spartans pitcher Mitchell Russell (2-0).
While Russell coaxed two harmless outs without allowing Orndorff to score, he couldn't escape a run-scoring balk that put Poly ahead, 2-0.
To Russell's credit, the senior rebounded and turned in a gritty 127-pitch complete-game effort in which he fanned nine batters, including striking out the side in the third, and allowed two runs (both unearned) on five hits.
Orndorff picked up the loss in his starting pitching debut, despite only allowing three runs (two unearned) on four hits, while striking out six.