SANTA CLARA, Calif. (AP) - Troy Smith's career easily could have been derailed two years ago during a frightening, monthlong bout with Lemierre syndrome, a rare and potentially fatal disease that began as a tonsil infection and progressed to his bloodstream.
He lost 40 pounds and had trouble breathing for 2 1/2 weeks. This all happened just before Baltimore's third preseason game in 2008, and the 2006 Heisman Trophy winner wasn't medically cleared to resume light workouts again until mid-September.
"Having the ability to breathe taken away from you for however long it was definitely is scary," Smith said Wednesday. "It definitely put a new perspective on life and what life is really about, and even though we love this game, it's just that. It's still a game and life is so much more precious, there's so much more going on."
Now, across the country with his new team - the San Francisco 49ers - Smith stands at a podium after a walkthrough practice as a confident NFL starter, having moved up the depth chart from third string in a matter of two months. He jumped over a pair of former No. 1 overall draft picks in the process.
Smith has performed so well for San Francisco, he will earn a third straight start behind center come Sunday against Tampa Bay, even now that previous starter Alex Smith is ready to return after separating his non-throwing left shoulder Oct. 24 at Carolina.
"My appreciation level, definitely just within a couple days, you wouldn't be able to see how appreciative I am of the opportunity," Troy Smith said. "I just have to take full advantage of it and hopefully that shows how important it is to me."
He hasn't thrown an interception in his two outings. He has fumbled once in each game, but the 49ers recovered both times. He has thrown for 552 yards, completing 29 of 47 passes.
Not bad for the guy who came aboard as the No. 3 QB initially getting no reps with the offense.
"He's a playmaker - that's what I'll describe Troy as," tight end Vernon Davis said. "He's not afraid to let the ball go. He wants to make plays, and he'll do whatever he has to do to make it happen."
The Niners took a chance on Smith after deciding to part ways with 2009 fifth-round draft pick Nate Davis, who later re-signed with the practice squad. Smith was a fifth-round draft pick by Baltimore in 2007 and had appeared in all of 14 games with two starts in three seasons. The Ravens cut him and he came out West to revive his career.
And has he ever. That despite being behind learning San Francisco's thick playbook. Not that he isn't comfortable with all the schemes.
"I would say probably out of 100, I am at 99.9 percent of it," he said.
Buccaneers coach Raheem Morris is plenty familiar with Smith's pleasant yet self-assured nature. Morris spent a week with Smith when Morris was a defensive backs coach in the Senior Bowl and Smith was playing. They enjoyed trash-talking across the field.
"He's dynamic. He lights up a room. He has all those unique qualities that you love about a quarterback," Morris said. "He led us to a Senior Bowl victory when we were there and I didn't have more fun with a guy than I did with Troy Smith."
It won't be quite the same if Smith takes it to Tampa Bay on Sunday.
He threw for 356 yards in a 23-20 overtime victory over St. Louis last week, carrying San Francisco (3-6) to a third victory in four games and keeping the Niners' playoff hopes alive following their surprising 0-5 start.
Though Smith knows full well he must keep playing like this - and better - to keep his job. He wouldn't want it any other way. Coach Mike Singletary plans to name his starter each week.
"It's something different each week. That's how I approach everything," Smith said. "If and when you start to think and worry about the things that happened to you in the past, you obviously take away from the things that can happen to you in the future. I truly believe that every situation is different from every other one. It has to be treated accordingly."
Smith's past certainly has featured its highs and lows, from his glory days at Ohio State to the downer of a serious illness early in his professional career.
"That happened to me for a reason. It helped strengthen my backbone, it helped strengthen my faith. It helped strengthen a lot of things for me," Smith said.
The 26-year-old Smith completed 40 of 76 passes for 113 yards and two touchdowns as a rookie in 2007, then the disease halted any momentum he gained in that first year. He went a combined 8 for 13 the next two seasons in limited action for the Ravens, who cut him in early September.
Receiver Ted Ginn Jr., in his first year with the 49ers, isn't at all shocked by Smith's emergence as a reliable starter. The two played together in college for the Buckeyes and also at Cleveland's Glenville High School.
They are godparents to each other's children and thrilled to be reunited.
"He's a fighter," Ginn said. "He will continue to get it done, no matter how hard it is or how easy it may seem, he's still going to work at it. Coming in, getting used to the guys, having two wins under his belt, that goes a long way. The only thing to do is keep pumping him up, keep that confidence in him. He should be able to just do whatever."
Notes: Barry Sims appears to be the leading candidate to replace injured LT Joe Staley, who broke his left leg against the Rams and is expected to miss four to six weeks. While Sims hasn't been active on game day yet this season, the 12th-year pro stepped in when Staley was sidelined for seven weeks in 2009 with a knee injury and gained the trust of the coaching staff. ... The 49ers signed K Shane Andrus to fill in again. Starter Joe Nedney will miss at least this Sunday's game after an MRI exam earlier in the week revealed a right knee strain and a bone bruise. Andrus was one of three kickers to try out Wednesday. He was with the Niners in training camp this year before being cut. He played in one game for San Francisco in 2009, when he also spent time with the Buccaneers and Indianapolis.