Instead of winning for the sixth time in California and for the seventh time on the trip, the Bucs lost, 3-2, despite allowing the Padres only one hit.
Furthermore, that one hit off Francisco Liriano was a bunt single -- with nobody out in the first inning.
"I don't think I've even been part of a game when you lose on one hit," said Pirates manager Clint Hurdle, a baseball lifer who has played and managed thousands of games.
It marked the first time the Pirates had lost a one-hit game since July 25, 1992, when the one hit was a David Justice home run that gave Atlanta a 1-0 victory.
The 45-year-old Padres won on one hit for the third time, duplicating feats in 2010 and 1975.
Josh Harrison tripled-up the Friars all by himself, with a triple and a double off right-hander Ian Kennedy, then another double in the eighth off reliever Joaquin Benoit.
But Harrison, playing second base, figured in both first-inning runs set up by Everth Cabrera's bunt single, then the Padres scored another run on a quartet of walks in the fourth.
The Bucs collected seven hits, including Andrew McCutchen's solo homer in the fourth, but that couldn't offset the nine walks issued by their pitchers -- a half-dozen by Liriano.
"Just a case of him wrestling with his delivery," Hurdle said. "Three of his five innings began with walks, and he's immediately pitching out of the stretch."
Brushing off the notion he had difficulty pitching out of the stretch, Liriano said, "I didn't have rhythm anywhere. Everything was down, or up and away. Any pitch."
"A weird day for me," Liriano said.
He was not alone.
"One hit ... but they did have a bunch of baserunners," Hurdle noted. "We had our hand in a couple of different scoring opportunities, and didn't execute. So we came up one run short."
Harrison was playing a new position -- starting at second base as Neil Walker got a day off -- but swung the same bat. His two-out triple in the third went for naught, but his fifth-inning RBI double cut the Padres' lead to 3-2.
The three extra-base hits gave Harrison his fifth multi-hit effort in the last seven games of the trip.
San Diego grabbed a 2-0 lead in the first, the bunt single being the inning's lone hit. Chris Denorfia led off with a walk and stole second before Cabrera pushed the bunt a couple feet off the first-base foul line -- perfectly placed among Liriano, first baseman Ike Davis, catcher Chris Stewart.
"He put it in the right spot. And it was a little confusing -- I wasn't expecting a bunt, not with a 3-1 count," Liriano said.
Carlos Quentin's sacrifice fly -- to Harrison, ranging into shallow center -- scored Denorfia.
"I played right field the other day, so I knew how deep [right fielder Travis Snider] was playing," said Harrison, who could hear Snider calling "Four! Four!" as he neared the ball.
So "Four," Harrison's position designation, took the ball -- but was off balance and not facing the plate when he made the grab and made his throw home to to try to nail Denorfia.
Another run resulted when Tommy Medica bounced back to Liriano for a force at second and Harrison's relay to first, attempting to complete a double play, skipped past the bag for an error.
McCutchen led off the fourth with his sixth homer and, four innings later, the Pirates did have a solid opportunity to strike and ruin the Padres' one-hit angle.
Harrison led off with his double into the left-field corner, putting him in scoring position for a promising gantlet: Walker, pinch-hitting, McCutchen and Davis. The first two flew to center, then Davis grounded out to third.
"Every hitter that inning had a swing at a [good] ball," Hurdle said. "Walker, he had a pitch very similar to the one he hit [Tuesday night, into the left-field stands]."
The Padres made it 3-1 in the bottom of the fourth, that time without a hit at all, but on four walks. Medica's began it, then two-out walks of Jace Peterson -- intentional, after Rene Rivera's grounder had advanced Medica -- Kennedy and Denorfia put the wrapping around the gift.
"Too many walks, getting behind the count too much. Not executing pitches. Three-two counts on almost every hitter," said Liriano, who in fact ran the count to three balls on a dozen of the 23 batters he faced.
Liriano was done after five, with an eccentric one-hitter. That first-inning bunt single remained the only "knock" against him, yet six walks and seven strikeouts ballooned his pitch count to 109. The lefty actually delivered more balls (55) than strikes (54).
The Pittsburgh bullpen kept the team within striking distance with its ordinary yet extraordinary combined effort. Jared Hughes, Tony Watson and Mark Melancon pitched three hitless innings. During this three-game series, Pirates relievers blanked the Padres for 10 1/3 innings on two hits.