ENGLEWOOD, Colo. -- The possibility that he had played his final snap in the NFL had occurred to Christian Ponder.

"Yeah, it crossed my mind," Ponder said. "My plan was to stay ready for the season anyway and see what happens. I think if nothing happened all year, it would be time to hang it up, but I was going to give myself this last season and see what happens."

What happened is what always happens in the NFL: Someone, multiple someones, got hurt. In this case, it was San Francisco 49ers quarterback Thad Lewis suffering a torn left ACL that ended his season in Sunday's preseason opener against the Houston Texans. That injury combined with Colin Kaepernick's tired right arm left the Niners set to practice with the Denver Broncos with only two healthy quarterbacks in the fold.

In other words, the 49ers didn't have enough signal-callers to get through practice, and if they did, sore arms might have awaited Blaine Gabbert and Jeff Driskel. So after stirring from his household chores -- including painting the house -- for a workout last week with the Arizona Cardinals, Ponder got the call from the 49ers after they found out Lewis' diagnosis. The team flew Ponder to the Bay Area from his Phoenix home at 8 p.m. PT Monday, he arrived at 10 p.m., woke up for a physical Tuesday morning, signed his contract and flew with the team to Denver on Tuesday night.

And oh, by the way, Ponder was on the practice field in a No. 5 jersey Wednesday morning with all of about 16 hours with the team's playbook under his belt.

"It's non-stop," Ponder said. "They gave me a playbook when I got on the plane, I studied the whole plane [ride], studied all last night and this morning and they threw me in the fire, which is good. It's the best way to learn. So it's been a fun 24 hours."

By his own admission, Ponder joins the 49ers a bit out of shape. The 28-year-old said he has some rust to knock off, and that was evident as he missed some targets during his first practice. He also didn't get much help with some drops. He did actually throw one of the best balls of the day for a touchdown to wideout DiAndre Campbell in 7-on-7.

In his time away from the game after spending bits of last season with Oakland and Denver, Ponder said he was working out in Phoenix with some Cardinals players, then switched to working out in his garage and throwing into a net in his front yard when the rest of the NFL was going through organized team activities.

"That's about how it went, real old-school," Ponder said.

Although Ponder still has plenty to learn in terms of the playbook, he said there was some level of understanding. When Ponder was in Oakland, he worked with offensive coordinator Bill Musgrave, whom he'd previously been with in Minnesota and who worked with new 49ers coach Chip Kelly in Philadelphia. According to Ponder, Musgrave had elements of what Kelly did with the Eagles installed with the Raiders.

Ponder also is plenty familiar with Gabbert and Kaepernick, who were also taken in the 2011 NFL draft. Ponder and Gabbert worked out together in the lead-up to that draft.

Perhaps the closest tie Ponder has with the 49ers is with offensive coordinator Curtis Modkins. Modkins recruited Ponder when he was coaching at Georgia Tech and once believed he was going to land him for the Yellow Jackets.

"He broke my heart back then and went to Florida State," Modkins said. "I reminded him of that when I saw him."

Of course, there wasn't much time to reminisce for Ponder and Modkins; the top priority is to get Ponder up to speed on the playbook. Modkins indicated Wednesday that the expectation is for Ponder to play Saturday night against the Broncos.

"He'll be fine," Modkins said. "He's smart. He's athletic. He'll be able to do the things we ask him to do and I expect him to be able to catch up to speed pretty quickly."

For a guy who once considered the possibility that his NFL career was over, there's no doubt what his intentions are for Saturday, preseason game or not.

"Yeah, I'd like to play," Ponder said. "It won't be the full playbook, but hopefully we come up with a plan of what I can do in a game and go out and play. It will be fun to compete and get out there."