San Francisco 49ers quarterback Alex Smith better lace up his running shoes.

Colts defensive end Dwight Freeney thinks he should have more sacks. And if Freeney thinks he should have more sacks, he's going to do everything in his power to get more sacks. Smith better start running. I'd suggest 7 a.m. Sunday, just for a head start.

Smith won the 49ers' starting job last week, nearly two years after losing it, fighting through injury and becoming synonymous for busted draft pick.

Welcome back, Alex.

Watch your back, Alex.

“I think I should have four or five (sacks) every game,” Freeney said. “Realistically, things happen. You miss plays. You miss sacks. That kind of drives you. I think I miss some every game. I think I've missed three or four every game.

“What game is it? I should have 21.”

Freeney says this with a smile, a look that says he's having the time of his life right now, and why not? His team is 6-0 and in firm control of the AFC South. He has seven sacks this season, fifth-best in the NFL, and is riding a streak of seven consecutive games with at least one sack.

The Colts' defense ranks second to the Broncos in fewest points allowed (12.8 per game) and has not allowed a touchdown the last eight quarters. With 16 sacks, the Colts are averaging almost three per game, and they rank sixth in fewest passing yards allowed per game.

Indianapolis starts a three-game homestand with a game against the 49ers (3-3) at 1 p.m. Sunday at Lucas Oil Stadium.

The return of Bob Sanders to the defense last week was a boost to the Colts' confidence, but the stinginess and pressure on opposing quarterbacks was already in full bloom.

Credit the bookends Freeney and Robert Mathis (4.5 sacks, three forced fumbles) with their pressure, but Freeney makes sure to spread the praise.

“People don't understand, everything has to work together,” Freeney said. “The secondary has to cover, the linebackers have to drop correctly, the opposite end and tackles have to play well. It's all a moving machine. When one thing breaks down, there's a greater chance for no sack.”

As Freeney emphatically puts it: “It's not just me, me, me making plays.”

Colts linebacker Gary Brackett, who calls the defensive plays before every snap, appreciates Freeney's words. Brackett acknowledges that sacks and quarterback pressure come from defensive cohesiveness.

But he also gives Freeney his due.

“Sometimes Dwight makes such great plays, he beats a guy,” Brackett said. “He's just great at pass rushing every time. More times than not, he gets there.”

Smith, Freeney's target this Sunday, came off the bench to complete 15 of 22 passes for 206 yards and three touchdown passes in the 49ers' 24-21 loss to the Texans. It marked Smith's first appearance in 28 regular-season games. San Francisco coach Mike Singletary named him the 49ers' new starter, supplanting Shaun Hill.

Singletary knows a thing or two about defensive pressure. He's beloved by Chicago Bears fans, and with good reason, for his ferocious style of play during some of that franchise's most storied seasons.

He knows what he's throwing Smith into this week.

Knowing that Freeney is on his way and keeping him at bay are two different things.

“I don't know if you can really game plan against a guy like that,” Singletary said. “He's spinning and turning and flying and doing all kinds of stuff coming off the ball. (We're) going to have our hands full trying to allow Alex enough time to throw the football instead of throwing on the run.”

The only real way to slow Freeney down is to run the ball effectively. That's where Frank Gore can make a difference, but only if he's the Gore of old. Gore had one big game this season (207 yards, including scores of 79 and 80 yards), against Seattle on Sept. 20. The next week he suffered a right ankle sprain and right hind foot sprain. He missed two games and returned last week to rush 13 times for 32 yards.

Gore says his ankle feels “pretty good,” which may or may not be the kind of shape it'll take to keep Freeney off Smith's back.

Freeney said sacks are unpredictable. There have been times he's hit the quarterback eight or nine times and recorded no sacks. Other times, he's hit them twice, and one went for a sack. Sometimes, as the Rams' Marc Bulger demonstrated last week, the quarterback will find a way to get rid of the ball a split second before the sack.

“The changing in the scheme has helped a little bit,” Freeney said. “It's not just me going. It's not just four (defensive linemen) against seven protecting, where they can double-team. Sometimes we have mixed in the blitz, and that causes them to account for more guys. … Maybe I can get that freebie. I haven't yet, but maybe I can get that one-on-one.”

Smith should consider himself forewarned.