It seemed to pay off.

Evan Longoria and Brandon Belt hit two-run homers, and Belt's blast in the 10th inning gave the Giants a 4-3 victory against the Diamondbacks and broke a four-game losing streak.

It was a step in the right direction for a team that had scored one or fewer runs in nine of its first 16 games. The Giants have scored the fewest runs in the majors (50) and are hitting a major league-low .159 with runners in scoring position.

The hitters met a day after getting only one hit, a check-swing infield single, in a 1-0 loss to Arizona left-hander Patrick Corbin on Tuesday. The Giants have been shut out three times this season.

"You're going to go through this during the course of a season, and you have to deal with it," Giants manager Bruce Bochy said. "I'm lucky I have a lot of experience with this club, and they can draw on it. Sometimes you need to back off (at the plate) a little bit, because they are grinding pretty hard. I hope they get some tension out and go back to being who they are.

"We're seeing some good pitching, but we're good hitters. Just think we are getting out of our game and getting to the point we are expanding (the strike zone) a little too much. I don't care who you are, you are going to swing at balls. You are going to chase occasionally. But I think consistently we have expanded the zone too much at this point. That can come from pressing."

The Giants expect to get a rotation reinforcement this weekend, when Jeff Samardzija is scheduled to start Friday in the first game of a three-game series at the Los Angeles Angels. He has not pitched this season after suffering a pectoral muscle injury late in spring training.

Arizona right-hander Zack Greinke (1-1, 5.29 ERA) is scheduled to oppose San Francisco left-hander Ty Blach (1-2, 4.43) in the final contest of the three-game series Thursday.

Walker, who was pulled after two innings of his start Saturday with right forearm tightness, received a second opinion Wednesday that confirmed a partial tear in his right ulnar collateral ligament. It was enough of a tear that a conservative approach -- rest, rehab -- would not be the best alternative, manager Torey Lovullo said.

Right-hander Matt Koch will fill Walker's spot in the rotation Friday and make his third career start. He started twice for the Diamondbacks in September of 2016 and made one relief appearance in 2017 and again this season during an earlier recall from Triple-A Reno.

Arizona was in a similar situation about this time last season, after right-hander Shelby Miller suffered an elbow injury that required season-ending surgery. Zack Godley used that opportunity to establish himself in the rotation.

"It is something that you need to build for," Arizona general manager Mike Hazen said. "You plan for injury, unfortunate as they are when they happen. No one is going to feel sorry for us. Injuries are going to happen all the time over the course of the league. We need to be able to find a way to overcome them.

"The position players have done a good job of that so far. Now it is going to be the pitchers' turn."

Chris Owings, Jarrod Dyson, Daniel Descalso and Deven Marrero have accepted bigger roles in the absence of right fielder Steven Souza and third baseman Jake Lamb. Souza has not played this season after suffering a shoulder injury late in spring training and Lamb has not played since suffering a left shoulder injury April 2.

"That's what good organizations do," Lovullo said. "They'll have somebody ready to step in a new role and help the team in a different way. That's what every player is waiting for. We're already doing that. We have guys stepping into different roles and it's been fantastic. We're winning games because of that depth."

Greinke suffered back spasms early in the first inning in his most recent start against the Dodgers on Friday. But after a brief break to stretch and twist he regrouped to pitch 6 1/3 innings, giving up five hits and four runs in an 8-7 victory.

He was 2-0 with a 1.83 ERA in three starts against the Giants last season and is 11-2 with a 2.37 ERA against the Giants in 17 career starts. Greinke won a major league-high 13 home games last season, going 13-1 with a 2.87 ERA in 18 starts at Chase Field.

Blach, now in his second season in the majors, was 0-1 in four appearances (one start) against the Diamondbacks last season, giving up seven earned runs in seven innings. He is 0-1 with a 9.45 ERA in three appearances at Chase Field, including his one start.