DENVER -- Quarterback Christian Ponder's game-winning touchdown pass on Saturday night wasn't exactly drawn up in the dirt. But in NFL terms, it wasn't far off.

Limited to a selection of about half of the 40 plays the San Francisco 49ers had installed for Saturday night's 31-24 preseason win against the Denver Broncos because he had just signed four days earlier, Ponder and the Niners found themselves adjusting on the fly with 6:20 left to go.

"We drew it up on the sideline," Ponder said. "It was a play that was already installed, they just told me and I hadn’t learned it yet. But we saw something and made an adjustment and it worked out well."

On second-and-6 from Denver's 30, Ponder got the look he wanted when the safety vacated the middle of the field. According to Ponder, receiver Dres Anderson running a post route was his third option on the play, but when the safety moved off his spot, Anderson became the go-to option. When running back Kendall Gaskins picked up a blitz up the middle, it gave Ponder enough time to let it fly and lead Anderson into the end zone.

Anderson hauled it in and provided the winning points for the 49ers.

"There is not a lot that has been installed to him, it’s just been talk about it," coach Chip Kelly said. "He understands it. I know that he has never run that play before he called it in the game. Maybe that’s how it should be more often.”

That touchdown capped an enjoyable return to football for Ponder, who hasn't taken a snap in a regular- season game since Oct. 2, 2014. Ponder spent time in the preseason with Oakland and had a brief stint with Denver last year, but didn't get on the field for meaningful snaps. When the 49ers called to bring him in earlier in the week, Ponder had been at home in Phoenix painting his house.

"It was fun," Ponder said. "I haven’t had that much fun on a football field in a long time."

After the Niners learned of Thad Lewis' season-ending knee injury, Ponder arrived on Monday, signed on Tuesday and was on a plane kicking off a crash course on Kelly's playbook by Tuesday night. He practiced on Wednesday and Thursday, acknowledging that he was out shape and had some rust to knock off along the way, but there he was coming into the game in the second half against the Broncos.

Although Ponder's damage came against the bottom of Denver's roster, he played well enough to make you think he'd been with the 49ers for all of training camp. He finished seven-of-eight for 86 yards and a touchdown and added a 22-yard run for another score to help the Niners pull away and prevent everyone from facing the horror that is preseason overtime football.

At this stage of camp, it would seem unlikely that Ponder could thrust himself into competing for the starting job, but it's not out of the realm of possibility he could win a roster spot.

“He kind of has a little bit about him," Kelly said. "We just have to put some things into terminology, but he had never run that play before. They just knew what they were doing, just trying to gang up on the run game, putting nine guys in the box so we have to have some force on the play action. I thought for Christian just getting here and taking snaps on Wednesday to perform like he did was kind of refreshing.”

Regardless of what happens next, Ponder is clearly happy just to be back playing football and cutting it loose with nothing to lose.

"I think what helped me the most was kind of stepping away for a year," Ponder said. "I think my confidence hurt towards the end of my years in Minnesota and I think that affected my game, and to kind of take a step back and take a breather and come back with a different approach, working on things mechanically during the offseason and building my confidence there, just to go out and have the mindset I just want to go and have fun. Like I said before, I didn’t have that much fun playing the last few years so it was great to get out there and have fun again."