Nobody will confuse the defensive line of the Houston Texans with some of the great units in National Football League history, even though it has three No. 1 draft picks. Nobody is going to bestow any nicknames such as the Fearsome Foursome or New York Sack Exchange on the unit.

But, at least one member of that line is deserving of any accolade that might be bestowed -- and he will be the focus today when the Steelers open their regular season at Heinz Field. Most definitely, he will be the focus for left tackle Marvel Smith.

Defensive end Mario Williams is not only difficult to stop, he is sometimes difficult to find, lining up on both sides of scrimmage and performing more stunts than an air-show pilot.

"They move him around the whole time," Smith said. "I think they move him around so offenses can't zero in on where he's coming from. And they run a lot of stunts with him as the key guy."

The decision to take Williams (6-6, 283) instead of running back Reggie Bush with the No. 1 overall pick in the 2006 draft -- a move panned at the time -- looks like a stroke of genius for the Texans.

He had 14 sacks last season, third most in the NFL, and is the lynchpin of a defensive line that features three No. 1 draft choices, along with tackles Amobi Okoye and Travis Johnson.

"He's turned into a fine pro," said Texans Coach Gary Kubiak. "He had a lot of pressure on him at first here, and that was put on him because of us and the decision we made. He is a very smart young man so we can ask him to do a lot of things. The future of our team had a lot to do with him becoming a fine player, and it sure looks like he is on his way."

The Texans rely on their defensive line to generate pressure on the quarterback because they don't like to blitz and leave their secondary exposed. That is especially true with the loss of Pro Bowl cornerback Dunta Robinson, who begins the season on the physically unable to perform list.

It is Williams who generates most of the pressure. The Texans had 31 sacks last season -- 10th in the AFC -- meaning he accounted for 45 percent of the sacks.

The problem for the Steelers has been protecting Ben Roethlisberger, who has been sacked 93 times in the past two seasons combined, more than any other NFL quarterback.

"He's like any other top dog -- he always comes relentless and he's big, strong, fast," Smith said. "He has all the tools you want in a good defensive end."

Williams' normal spot on the defensive line is right end, across from Smith. But the Texans will line him on the other side, too, and runs stunts -- looping him from the outside and having him rush up the middle.

It is those kind of tactics that can create confusion in the offensive line, particularly a unit with two new starters who are still learning to communicate with each other.

"I think they do it better than other teams," Smith said. "They execute those stunt and they run them to perfection. You definitely can see it's something they practice a lot, especially for young guys running those stunts. They do it better than anyone."