Near the end of the preseason, and even in the 49ers' season opener and first few weeks of the regular season, the 49ers used Trey Lance in different packages -- especially in the red zone or running situations.
The plan worked to perfection at first. Lance connected with Trent Sherfield for a 5-yard touchdown on his first pass attempt in the NFL, giving the 49ers their first points this season in Week 1 against the Detroit Lions. But as the season wore on, Lance's time dwindled, aside from starting Week 5 against the Arizona Cardinals for an injured Jimmy Garoppolo. Shanahan admitted in late November that the reasoning had more to do with him as a play caller than Lance as a QB.
But after Sunday's 23-7 win over the Houston Texans with Lance leading the way, Shanahan already feels more comfortable calling plays for the young rookie.
With our All Access Daily newsletter, stay in the game with the latest updates on your beloved Bay Area and California sports teams!
SIGN UP HERE "I've done it for two games here, but we talk about it all the time," Shanahan said. "He goes through all the stuff that we go through with Jimmy. I feel real good with it, especially for only doing that twice.
"That's something that you always -- player and coach -- you always get more comfortable the more games you get."
Lance completed 16-of-23 pass attempts for 249 yards with two touchdowns and one interception. He ran eight times for 31 yards, and Sunday was the first time he attempted a pass in nearly three months.
Back in Week 5, Lance completed 51.7 percent of his passes in a 17-10 loss to the Cardinals. He had a QB rating of just 58.4. On Sunday at Levi's Stadium, he completed 69.6 percent of his passes and finished with a QB rating of 116.
San Francisco 49ers
Find the latest San Francisco 49ers news, highlights, analysis and more with NBC Sports Bay Area and California.
"I thought Trey did some really good things," Shanahan said. "He was thrown into a real tough situation in terms of where our team was at and how big of a game that was, basically being a playoff game. I thought he went in there, handled the pressure real well, got off to a slow start -- him and the rest of the offense -- which I thought put a little more pressure on him also.
"Just to watch him respond, especially after that pick, I thought he had a real successful day to get the first win off his back."
RELATED: Maiocco: Jimmy G-Lance decision for Week 18 has no easy answer
With only 38 seconds left in the first half, Lance drove the 49ers down the field by going 3-of-5 passing for 56 yards to get them into field-goal position. A 37-yard Robbie Gould field goal gave the 49ers their first points of the day, and cut San Francisco's deficit to four points.
This was just two series after Lance's interception on a pass intended for tight end George Kittle. It also gave him a big confidence boost, and the 21-year-old had much better control of the offense in the second half.
Shanahan also said that Lance's throwing motion is shorter compared to the start of the season, and the Texans actually had to stack the box more with Lance at QB for his ability to run. It's clear that Lance kept Houston guessing and on its toes, especially with how he extended plays and completed passes all over the field.
As far as the plan going forward, Shanahan is holding out hope that Garoppolo can practice Wednesday and will have game plans for both quarterbacks ahead of Sunday's matchup with the Los Angeles Rams, with the playoffs on the line in the regular-season finale.