SAN FRANCISCO -- It immediately felt like a moment the Phillies would regret.

Giants pitcher Johnny Cueto walked with two outs in the fourth inning Friday night at Oracle Park. Cueto had a .100 career batting average and no hits in 14 at-bats this season. He had not walked since June 3, 2017. But Phillies right-hander Vince Velasquez walked him on five pitches. LaMonte Wade Jr. followed, drilling a 1-0 fastball to center field for a triple. Odúbel Herrera had a play, but he could not catch it.

Cueto scored to hand the Giants a one-run lead in a 5-3 victory.

• Box score

“That’s just unnecessary,” Velasquez said. “I have to get that guy out. Cueto is not going to get on by bunting or hitting. I have to get that guy out. It’s just a mandatory out.”

The Phillies suffered from self-inflicted damage throughout the night. They played particularly sloppily in the second inning to hand the Giants a 3-1 lead.

“I thought we’ve played good baseball the last two weeks or so,” Bryce Harper said. “We can’t make the little mistakes. If you make the little mistakes, they’re going to haunt you. You guys know that. We need to be better at doing that. I thought we played pretty good ‘D’ in L.A. Tonight was just one of those nights.”

Herrera got completely turned around on Brandon Crawford’s fly ball to center field to start the second. The ball should have been caught, but it fell next to him for a double. Crawford got to third when Velasquez threw a first-pitch slider into the dirt to Steven Duggar, who walked with one out to put runners at the corners. Duggar stole second to put runners at second and third.

Jason Vosler singled to right. Harper made a heads-up play and deked Crawford, who started to go back to third, only to realize the ball had fallen for a hit. Crawford sprinted home, but Harper’s throw missed its mark. Wade then ripped a ball off Rhys Hoskins’ glove for a two-out double to score Duggar to make it 2-1.

“Both balls are smoked,” Phillies manager Joe Girardi said. “The reaction time, there’s not a lot. Your reads have to be perfect or you’re not going to make the play.”

Vosler scored on a passed ball to make it 3-1.

Two catchable balls not caught, one offline throw, one walk, one wild pitch and one passed ball in one inning cost the Phillies three runs. One two-out walk to a pitcher cost the Phillies one run in another.

It is why they fell to 33-34.

“It could have been a different game if we play a clean inning,” Girardi said. “Take away the walks and we play a clean game and it’s a different game. We’ve been much better of late, but we’ve had our share of those.”

Harper returned to the lineup after leaving Tuesday’s game in Los Angeles because of lower back spasms. He did not play Wednesday, giving him two consecutive days off, and he had an interesting return. He thought he lined out to Crawford in the first inning, so he did not bust out of the box. The ball dropped to turn an easy 6-4-3 double play. In the fourth, Harper hit a fly ball down the left-field line that he thought was foul, but it sliced back into fair territory, so he only got a single out of it.

“I’ve never seen that before actually,” Harper said. “But man, it was in the stands. I was watching, watching. I was like, oh, man, that ball is coming back. I got caught right there and I need to be on second base, of course. I need to be better.”

He then ripped a ball off the left-field wall in the sixth, but Wade threw him out at second base.

“I thought he just made a really good throw,” Harper said.

But Harper said the back feels good. It is good news, because the Phillies need him 100 percent to have a chance to beat the Giants over the weekend. The Phillies are 1-3 on this six-game road trip.

“I think just traveling and things like that kind of got me after that first game [in Los Angeles],” Harper said. “I went out there, took a swing. I thought I could stay in the game and they kind of just wanted to get me out of there just in case -- precautionary. I felt good today going out there. You’ll see me going out there tomorrow and the next day and playing well.”