SAN FRANCISCO -- A Giants team that prides itself on resiliency was beaten at its own game Saturday night.

The Reds lost Game 1 starter Johnny Cueto after just eight pitches, but the Giants couldn't take advantage, losing 5-2 and falling behind in the best-of-five National League Divisional Series. Matt Cain gave up two big homers, and five Reds pitchers combined for 82/3 relief innings as Cincinnati stole a game at AT&T Park.

Cueto had trouble warming up and looked uncomfortable from the start. He retired just one hitter before being pulled with back spasms.

"When Johnny went down, I was like, 'Oh, man, we're done,' " Reds second baseman Brandon Phillips said. " 'Why? Why?' "

The Giants found themselves asking, "How? How?"

How could they give this one back?

Instead of facing a fellow Cy Young Award candidate, Cain eventually squared off against Game 3 starter Mat Latos, who made his first career relief appearance. Latos lasted nearly as many innings as Cain did, giving up just a Buster Posey homer in four crucial relief innings.

After Cueto left, the Giants managed just one hit in 12/3 innings off immediate replacement Sam LeCure, who was followed by Latos.

"It was a little bit of a curveball for both teams," Giants right fielder Hunter Pence said. "But it's still going to be a grind."

Only one team found a way to grind out the rest of the night, and it wasn't the one that overcame a season-ending injury to its marquee closer and a 50-game suspension for its All-Star left fielder. Cain has been a guiding light in a season built on overcoming adversity, but his outing Saturday was a short one.

The Giants' ace entered the night with 211/3 career scoreless innings in the postseason but was taken out after he gave up three runs on two homers in just five innings. Phillips hit a two-run shot on a hanging curveball in the third inning; Jay Bruce hit a blast to right in the fourth.

"That's just something that you don't want to happen in a big-game situation," Cain said. "The hanging breaking balls in these games always hurt a little bit more. I made some bad pitches and put these guys in a hole.

"That's my fault."

The Giants tried to hit their way out of the hole but never could quite find one. Cain had hit a bases-loaded shot to right in the second but had nothing to show for it. Pence twice thought he hit balls as well as possible but watched the shots die in the damp San Francisco air.

Pence reached on an error to lead off the fourth but was immediately doubled off when Brandon Belt scorched a shot right at first baseman Joey Votto.

"We had a tough night," manager Bochy said. "I thought we had better at-bats than what it looked like. We didn't have a lot of things going for us."

The Reds did, in a very unorthodox way.

Latos had thrown 78 pitches Tuesday and was scheduled to start this coming Tuesday, but he was rushed into duty and handled it with aplomb. A longtime Giants nemesis because of comments he made in 2010 while with the San Diego Padres, Latos handed a 3-1 lead to the traditional members of a bullpen that led the majors in ERA this season.

Still, the Giants had a chance.

Left-hander Sean Marshall set down the Giants in order in the seventh, but they got two runners on against Jonathan Broxton in the eighth. The former Los Angeles Dodgers closer went to a full count on Gregor Blanco before striking him out looking on a fastball that could have been called either way.

"I thought it was a little outside," Blanco said. "But the umpire makes a decision. It was a tough call for me, but it happens."

Against the odds, the Giants twice brought the tying run to the plate in the ninth. The Reds scored two in the top of the inning to hand a 5-1 lead to Aroldis Chapman, an All-Star closer who regularly touches triple digits.

But Chapman was wild, and he loaded the bases on a single and two walks. A wild pitch scored one, but Chapman retired Pablo Sandoval and struck out Posey swinging on 100 mph fastball.

"We can bounce back," Pence said. "I've got all the faith in the world in us."

The problem for the Giants: After overcoming a serious obstacle of their own Saturday on the road, the Reds feel the same way.

"This is a resilient team," Reds manager Dusty Baker said. "They can pick each other up and go on."

Only one team will, and at the moment, it's not the Giants in the driver's seat.

For more on the Giants, see Alex Pavlovic's Giants Extra blog at blogs.mercurynews.com/Giants. Follow him on Twitter at twitter.com/AlexPavlovic.