SAN FRANCISCO -- The Giants doubled down on their youth movement on Tuesday by parting ways with veteran shortstop Nick Ahmed, who was designated for assignment to create more opportunities for young players like Brett Wisely and Tyler Fitzgerald.

The two infielders rewarded that faith hours later, as Wisely delivered a game-tying hit and Fitzgerald homered and scored the winning run on a wild pitch to propel the Giants to a 4-3 walk-off win over the Blue Jays in Tuesday night’s series opener at Oracle Park.

The Blue Jays seized a 3-1 lead behind Ernie Clement’s three-run, go-ahead homer off Ryan Walker in the seventh inning, but the Giants got one run back via Fitzgerald’s eighth-inning solo shot and then completed their comeback in the bottom of the ninth.

Patrick Bailey singled and Fitzgerald drew a two-out walk to put a pair of runners on for Wisely, who tied the game with an RBI single that deflected off the glove of a diving Leo Jiménez at second base. Fitzgerald advanced from first to third on the play and then dashed home after catcher Danny Jansen couldn’t corral Trevor Richards’ two-strike changeup in the dirt, giving the Giants their eighth walk-off win of the year, one behind the Marlins for the most in the Majors this year.

Fitzgerald became the first Giant to score on a walk-off wild pitch since Nate Schierholz on June 20, 2009, against Texas.

“I was like saying in my head, ‘Please throw a dirt ball, please throw a dirt ball,’” Fitzgerald said. “Even if it wasn’t that far away from him, I was still going to try to score there because [there were] two strikes on Thairo [Estrada]. Anything in the dirt, I was going to try, unless he blocks it perfectly. I guess I spoke it into existence.”

Fitzgerald struck out swinging in his first two at-bats of the night against Blue Jays left-hander Yusei Kikuchi, but he drilled a misplaced fastball over the left-field wall for his second homer of the season in the eighth and then came back from a 1-2 count to work a seven-pitch walk against Richards in the ninth.

“That was huge,” manager Bob Melvin said. “Those are the types of things that might not be the most exciting things in the world, but it sets it up.”

Fitzgerald, 26, has bounced between Triple-A Sacramento and the Majors this year, but he should have a better shot at sticking now that the Giants have moved on from Ahmed. Wisely is expected to serve as the primary shortstop, but Fitzgerald figures to start against lefties and continue to receive plenty of pinch-running opportunities off the bench.

“We’ve talked a lot about wanting to give some of our young players coming up opportunities and adding athleticism to the roster,” president of baseball operations Farhan Zaidi said. “The best way to do that is to have your young guys come up and earn roles. It’s as much as anything just a vote of confidence for those guys. [Luis] Matos and Fitz in particular, they’re guys who have been a little bit on the up-and-down shuttle between here and Sacramento. Hopefully this is an opportunity for them to feel like they don’t have to look over their shoulder and continue a lot of the positives that we’ve seen with them.”

The late rally kept the Giants from squandering an encouraging start from left-hander Blake Snell, who is finally beginning to find the form that earned him his second career Cy Young Award last year.

Snell, who returned from the injured list after missing more than a month with a left groin strain, allowed only one hit over five scoreless innings, marking his longest outing since signing a two-year, $62 million deal with the Giants in March.

The 31-year-old left-hander walked three and struck out three while topping out at 97.7 mph, his highest velocity of the season. The Giants had him on a pitch count in his first start since June 2, prompting the club to remove him after he threw 73 pitches. Snell departed with a 1-0 lead thanks to All-Star center fielder Heliot Ramos, who opened the scoring by blasting his team-leading 13th home run of the season off Kikuchi in the fourth.

“I still think I’ve got a lot to learn with who I want to be this year,” said Snell, who went 0-3 with a 9.51 ERA over his first six starts of the year. “Every year is a new canvas. I think I’m a lot better. I think I understand myself. I can repeat deliveries. I like the way I’m talking to myself. I’m excited for the Twins, excited to see these next four or five days how I grow and what I work on. Just looking forward to that next one.

“Probably like three or four more starts to really put it all together and then start repeating really good outings. But I’m happy with this one. I just know there’s a lot that I can do to get better.”