DENVER -- The Padres placed catcher Francisco Mejía on the 10-day injured list on Saturday with a left knee sprain and called up catcher Austin Allen from Triple-A El Paso.

Padres manager Andy Green said Mejia has been dealing with the knee issue off and on most of the season. Following the game Friday night, it was bothering him more, Green said.

"It's never been something that was overwhelming for him, but we thought, ‘Let's take a week off here and give it some time to calm down,’" Green said. "There were probably a couple of times over the course of the season where we were trying to give him a start or two and pulled him back because of it. At this point in time, let him rest, let him recover, let him get back."

Allen is San Diego's 19th-ranked prospect, according to MLB Pipeline. The 25-year-old backstop has hit through every level of the Minors, with 22 home runs in each of the last two seasons between Class A Advanced Lake Elsinore and Double-A San Antonio. In 27 games for El Paso this season, he was hitting .279/.358/.529 with six homers.

"I've got every single emotion you can have," he said Saturday before the Padres’ 4-3 victory over the Rockies at Coors Field. "Nervous, excited, happy. It's been a long time of hard work and dedication. I'm definitely glad to be here."

Allen made his big league debut with a pinch-hit walk off Rockies closer Wade Davis in the ninth inning. That walk loaded the bases and preceded Greg Garcia's go-ahead RBI fielder's choice ground ball.

Austin got the news that he was going to the Majors following his first at-bat Friday against Albuquerque, coincidentally, the Rockies' Triple-A affiliate.

"I came back into the dugout,” Allen said, “and Chris Stewart was putting on his leg guards and stretching out, and our manager goes, 'Hey, Austin, come here.' And I'm like, ‘I know I didn't have that good of an at-bat.’ I didn't know what was going on. He pulled me down into the tunnel and told me I was going to the big leagues."

Though Allen wasn't in the lineup Saturday, Green said he'll be starting behind the plate Sunday in the series finale. Allen said he's confident the nerves will transition into comfort in due time.

"It's just baseball," he said. "Being up here with all these guys, it's going to slow it down a little bit. And [whenever] I get out there, after the first pitch, it turns into just baseball, no matter how big the stadium is or how many people are there."

The Padres could use an offensive spark from the catcher position. San Diego catchers are hitting .170/.236/.296 with four homers.