FOXBOROUGH, Mass. Aldon Smith doesn't have especially prominent incisors. And he doesn't have an abundance of facial hair.
But something definitely seems to stir inside the 49ers outside linebacker when the sun goes down.
Smith enters tonight's game against New England within striking distance of the NFL's season sack record and with a growing reputation for becoming most ferocious in prime time.
That began last season when, on "Monday Night Football," Smith had 2 1/2 sacks and seven quarterback hits against the Steelers' Ben Roethlisberger. This year, 10 of Smith's league-leading 191/2 sacks have come in four prime-time games, including 5 1/2 sacks against the Bears on Nov. 19, the most anyone ever has had on Monday night.
Smith admitted feeling an extra jolt of electricity when the night comes. He said it has been that way since high school.
"Those Friday night lights," said Smith, 23. "You knew it was showtime. It's just that feeling you get again from being under that spotlight."
The 49ers will need a bit of Smith's full-moon fever against quarterback Tom Brady and the Patriots in a game that features two excellent teams with opposing strengths.
New England averages the most points, 36.3, in the league and hasn't been shy about pouring it on even when the outcome no longer is in doubt.
The 49ers' defense, meanwhile, has been the league's stingiest. It hasn't allowed a touchdown in five games this year and has held opponents to an NFL-low 14.2 points a contest.
The Patriots have the league's top offense; the 49ers rank No. 2 in passing defense, rushing defense and overall defense.
Then there's the battle for Brady's well-being.
New England has given up just 20 sacks this season partly because of the quarterback's savvy and quick release, and partly because of an offensive line that 49ers defensive coordinator Vic Fangio said is one of the two most well-coached units in the league. (Fangio said Patriots offensive-line coach Dante Scarnecchia's bunch ties with Mike Solari's 49ers for that honor.)
The biggest key is whether the 49ers can rattle one of the game's best quarterbacks, something they were able to do earlier this season at Green Bay and New Orleans.
That's where Smith comes in.
Since the NFL began recording sacks in 1982, no one has been as torrid. At his current pace, he will finish with 24 sacks, 1 1/2 more than the season record holder, Michael Strahan, in 2001.
"Smith has a good combination of skills," Patriots coach Bill Belichick said last week. "He's strong. He can power rush. He can rush the edge. He's quick. He's got a good up-and-under move. He's got an outside move. He's got an inside move. And he can run over those guys. That's three pretty good pitches right there."
The player lining up across from Smith today can attest to the linebacker's strengths.
Like Smith, Patriots left tackle Nate Solder was a first-round draft pick last season. They faced each other in 2009 when Solder played for Colorado and Smith was a redshirt freshman at Missouri.
Smith had three sacks and four tackles-for-loss as Missouri won 36-17.
"I'm sure he's improved," Smith said of Solder. "He's made it this far. He's starting, so I assume so. I haven't watched that game in a long time, but I was able to get past him and create pressure back there."
Belichick said Solder takes on the opposition's sack leader just about every week.
"Nate's a good player in his own right," Belichick said. "He's competed against a lot of good rushers this year and last year."
Smith's main adversary, however, is Brady, who has thrown 29 touchdown passes and just four interceptions and is tied with the Redskins' Robert Griffin III for the league's highest passer rating.
During last week's Sunday night broadcast, NBC promoted tonight's game by showing a picture of Brady on one side of the screen. Representing the 49ers on the other side was the man who figures to be chasing Brady all night.
Smith said he learned of the juxtaposition when a friend sent him a picture of the promo.
"I just had one word 'Wow,' " he said. "I didn't know what to say. It's Tom Brady. He's won Super Bowls. Me? I just got here."