An 0-for-11 slide had dropped his average to .195. He had struck out three times and walked in his first four times up.
He fouled off a fastball from Pedro Baez, then hooked a 97 mph belt-high pitch high down the right-field line. Would it stay fair?
"I saw it hooking, and I've been having issues with that," Granderson said. "It stayed fair just long enough."
But in a non-save situation, Familia (2-0) allowed three singles, walked Yasmani Grandal with the bases loaded and gave up a two-out, three-run double to Chase Utley, who was booed all night in his first game action at Citi Field since breaking a leg of Ruben Tejada in last year's NL Division Series. Utley had four RBI.
"It was only fitting," Dodgers manager Dave Roberts said.
Granderson, a 35-year-old, three-time All-Star, was just trying to get on base leading off the bottom half. His only previous walkoff homer was for Detroit off Cliff Politte of the Chicago White Sox on Sept. 26, 2005.
Baez (0-1) has been troubled by long balls -- the home run was the fifth he's allowed in 21 innings. Granderson got his eighth homer and 14th RBI of the season.
"He stays level. He doesn't get too down. He doesn't get too carried away with success," Mets manager Terry Collins said. "You never know if he's 10 for 10 or 0 for 10."
With its sixth victory in seven games, New York moved back into the NL East lead, by percentage points over Washington, giving Collins a happy 67th birthday. The Mets stopped the Dodgers' four-game winning streak.
Utley, who didn't play in Games 3 and 4 of last year's Division Series, was greeted with loud jeers and derisive chants. He walked leading off the game and slid well ahead of second base when he was caught stealing as Corey Seager struck out, then hit a sacrifice fly in the third off Jacob deGrom.
He was 3 for 7 in his career against Familia when he came up with the bases loaded, turned on a 98 mph pitch and sent it on two hops to the fence in right-center. The slow-footed Grandal easily beat the off-line relay throw from second baseman Neil Walker.
Roberts said Utley had put last year's incident behind him. During the offseason, Major League Baseball banned takeout slides in what some call the Utley Rule.
"The way he plays the game is the way he's always played the game," Roberts said. "There are slides like that every single night that don't have that result. I know he feels bad."
DeGrom allowed one run, three hits and three walks in seven innings, lowering his ERA to 2.81. His fastball, which averaged 93-94 mph coming in, was back up to 96 mph -- its level last season.
"Arm slot's a little better. I was throwing the slider to both sides of the plate," he said. "I had more swings and misses on my fastball tonight than I had early on. That tells me it's got a little late life to it."
THANKS FOR THE MEMORIES
Most members of the 1986 Mets are expected to attend a pregame ceremony Saturday.
Walker had an RBI double with two outs in the first, Lagares followed with a two-run single and Kevin Plawecki singled, stopping an 0-for-17 skid. Coming in, the Mets were hitting .159 (24 for 151) this season with two outs and runners in scoring position.
Mets: Wilmer Flores (left hamstring) made his fourth start in an injury rehabilitation assignment at Double-A Binghamton, playing all nine innings at first base and going 1 for 4.
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