SAN FRANCISCO --  Michael Papierski was so close to being a big league catcher last fall he could smell it. After five seasons in the Minors, he was on the Astros’ taxi squad during last year’s Division Series against the White Sox and took special notice of all the pitchers he got to study. In Game 4, that included Chicago’s Carlos Rodón.

“It was a really cool being in the dugout and experiencing that first-hand," Papierski said.

Not nearly as cool as Papierski’s experience on a gorgeous Saturday afternoon at Oracle Park, when he got to catch Rodón in his Major League debut just one week after the Giants acquired the 26-year-old from Houston in the Mauricio Dubón deal.

Papierski struck out in each of his two at-bats in a 2-1 loss to the Padres, the Giants’ third in a row, which sealed a series loss to a San Diego team that finally looks ready to challenge the Giants and Dodgers for National League West supremacy.

Papierski had company. The Giants mustered four hits and no runs against Joe Musgrove in seven innings, including a single and double by the right-hander’s biggest tormenter over the years, Joc Pederson.

Nonetheless, Papierski got a cap tip from his pitcher. Rodón had what he termed an “inefficient” six-inning start (two runs, four walks, six strikeouts) after he barely had time to learn his catcher’s name, much less prep with a new batterymate who was not activated until 90 minutes before first pitch.

“I thought he did well, making his Major League debut against a pretty good team,” Rodón said. “He came from the Astros and has been here, what, one week? That’s a tough calling. I thought he did great. I really did.”

Papierski got the promotion from Triple-A Sacramento when Curt Casali, who had gotten most of the starts of late, went on the seven-day concussion list. Casali took a wicked foul ball off his mask in the seventh inning of Friday night’s loss. The Giants believe Casali could return when eligible on May 28.

Joey Bart had to strap on the gear quickly to replace Casali and came to work Saturday with back tightness, manager Gabe Kapler said when asked why Papierski started over Bart, who was nonetheless available and played two innings after Evan Longoria pinch-hit for Papierski in the seventh inning.

A lot of Minor Leaguers talk about the “whirlwind” of their first callup. For Papierski, this was no cliché.

A week earlier he was a Sugar Land Space Cowboy in the Pacific Coast League. Now he was squatting before tens of thousands of fans, getting an up-close view of the National League’s best hitter, Manny Machado, slamming a top-of-the-zone, 99 mph Rodón fastball 425 feet for his eighth home run, a solo in the third inning.

The Padres scored their other run in the sixth on a safety squeeze from Trent Grisham. The Giants’ run came on Wilmer Flores’ fourth homer, in the eighth off Robert Suarez.

Papierski, a switch-hitter, said the catching portion of his first big league game felt much more comfortable than his hitting. He did not lift the bat off his shoulder during a five-pitch strikeout in the third inning. Musgrove got him on three pitches in the fifth, the final two swinging. With two outs and two on in the seventh inning of a 2-0 game, Kapler had Longoria bat for Papierski hoping for one big swing to tie the game or give the Giants a lead.

“At the plate, the game sped up a little bit,” Papierski said. “I tip my cap to Joe. He made some good pitches today. I’ve got to slow the game down a little bit, but you know what? Debut is over. The nerves are gone. Now it’s time to go to work.”

Although he had not set foot at Oracle Park before Saturday morning, Papierski does have one oblique Giants connection. He is extraordinarily tight with Ryan Theriot, the now-retired infielder who scored the winning run in the clinching game of the 2012 World Series at Detroit.

Both are from Louisiana and Papierski works out at Theriot’s baseball facility in Baton Rouge, a few minutes from Papierski’s house. They go back to the catcher’s days at LSU, when Theriot began to school him in the physical and mental aspects of high-level ball, guiding Papierski through his struggles.

“He’s a father figure for me,” Papierski said. “He’s one of a kind, one of my favorite people.”