Young singled off Giants' reliever George Kontos with an out in the 16th and stole second. He took third on a ground out and Kontos was replaced by Javier Lopez.
Lopez intentionally walked David Wright and Anthony Recker was called on to pinch-hit. He hit a grounder to short that Brandon Crawford misplayed for an error, allowing Young to score.
Crawford had been the San Francisco hero until that point, with three hits, including an RBI single in the seventh tying the score 3-3 and a very nice play ranging to his right to end a Mets' threat in the 11th.
Kontos (2-2) allowed just the single to Young in 2 2/3 innings of relief but still got the loss. Josh Edgin (1-1) also allowed just one hit in two innings in taking the win, the Mets' third in four games. Bobby Parnell, despite giving up a single and walk in the bottom of the 16th, earned his 16th save.
Buster Posey hit a two-run home run for San Francisco in the first inning. New York's John Buck doubled in Marlon Byrd in the fifth and the Mets went up 3-2 the next inning when Daniel Murphy singled in Young, who opened the inning with a triple, and scored the go-ahead run on a double play.
Hunter Pence tripled leading off the San Francisco seventh just ahead of Crawford's RBI single that tied the score.
Ray Liotta sues skin care company over use of likeness
Boston schools pull out free condoms over wrapping complaints