PHOENIX -- The list of mistakes rolled off A.J. Hinch's tongue Monday night.

"We had two bunts on offense we didn't get down, we had three errors, we misplayed a ball on defense, numerous leadoff walks," the D-backs manager said. "It's not winning baseball."

It all added up to a 5-4 loss to the Giants at Chase Field.

"It was a sloppy game," third baseman Mark Reynolds said. "We rallied back and tied it up. We had our chances all night and we had some sloppy play, and they out-executed us and it's a tough loss."

Reynolds gave the D-backs a 2-1 lead in the first when he hit a first-pitch fastball from Giants starter Barry Zito into the left-field bleachers for his 43rd homer of the year.

"Past history with him, I know he's either going to start me off first-pitch curveball or heater in, and I was just sitting on it and got it," Reynolds said. "It feels like the first ball I've barreled up in about a week."

Not quite a week, but the Arizona slugger has been struggling at the plate. Coming into that at-bat, he was in an 0-for-16 slump.

"I didn't even know I was 0-for-16," Reynolds said. "I just go out there and play. I hit in the cage and just tried to get my swing path back. It got a little loopy there for a while, and tonight I felt good at the dish and had some good passes."

The Giants tied the game in the fourth and went up, 4-2, thanks to a two-run fifth inning.

Arizona, though, answered right back with a two-run fifth of its own, thanks to a two-run single to right by Justin Upton that tied the game at 4.

That's where things stood when reliever Esmerling Vasquez walked Travis Ishikawa to open the eighth inning.

"I think it caps a night of really, really poor execution," Hinch said. ""We practice it, we talk about it, we try to get better, and it kind of rears its ugly head every now and then."

Aaron Rowand followed Ishikawa and pushed a bunt between the pitcher's mound and first base, and Vasquez collided with second baseman Ryan Roberts trying to make the play. While on the ground, Vasquez tried to throw Rowand out at first, but instead, the ball sailed past first baseman Brandon Allen to put runners at second and third.

Making the play even more costly was the fact that Roberts mildly sprained his right ankle in the collision and had to leave the game.

"It's all right, it's a little sore right now," Roberts said. "It could have been worse."

One out and an intentional walk later, Fred Lewis hit a grounder to second baseman Augie Ojeda that the D-backs attempted to turn an inning-ending double play on. Lewis, though, hustling all the way, just barely beat the throw to first as Ishikawa came home with what proved to be the winning run.

Sergio Romo (5-2) earned the win in relief, while Vasquez (3-3) suffered the loss.

"We stayed in the game, which was good, and didn't let it get away from us," Hinch said. "But we just made too many mistakes to win a game against a good team."

Said Roberts, "It was a rough night, a rough loss."