Even when they look like they’re sleepwalking through much of the game, the Giants are good enough to win by four touchdowns.

The Giants didn’t always look good during their 41-13 win over the Rams in St. Louis yesterday, but they showed off a balanced, turnover-free offense and a stout defense, and they generally looked like they’ve picked up in September pretty much where they left off at the Super Bowl in February. And that was on a day when they didn’t really pull away until the fourth quarter, despite playing against one of the worst teams in the NFL.

Eli Manning had impressive numbers, completing 20 of 29 passes for 260 yards, with three touchdowns and no interceptions. On the ground, the Giants’ offensive line showed that it could open gaping holes no matter who is getting the ball. Brandon Jacobs ran 15 times for 93 yards, Derrick Ward ran eight times for 58 yards and Ahmad Bradshaw ran five times for 52 yards, all behind a line that manhandled the Rams’ front four all day. Right guard Chris Snee was particularly impressive and showed surprising agility when pulling to the left to block a St. Louis defensive back, which he did several times.

And yet even on a day when the Giants scored 41 points, gained 441 yards and had 25 first downs, there was a sense that the offense could have done more. Manning missed open receivers several times. On two plays in the second quarter, Amani Toomer and Steve Smith were wide open for what could have been touchdown passes, only to have Manning overthrow them.

Manning also shows a tendency to rely too much on his starting wide receivers, Toomer and Plaxico Burress. The pair caught 11 of Manning’s 20 completions yesterday, and at times he appeared to be forcing the ball to them even if he had a better option elsewhere. And while Manning did spread the ball around a little bit, completing passes to eight different receivers, none of those receivers was a tight end: Starter Kevin Boss did have a 28-yard catch called back by a penalty, but in two games this season he still doesn’t have a catch that shows up in the box score. There were times when the Giants looked like they could have used Jeremy Shockey, who is now with the New Orleans Saints.

Surprisingly, the Giants never looked like they missed Michael Strahan or Osi Umenyiora. Even though last year’s starting defensive ends are gone, the Big Blue pass rush looked every bit as strong against the Rams as it was in 2007, when the Giants led the league in sacks. Defensive end Justin Tuck had a tremendous game: He sacked Rams quarterback Marc Bulger twice, tackled running back Steven Jackson at the line of scrimmage once and intercepted a pass and returned it 41 yards for a touchdown in the fourth quarter. Fred Robbins added two sacks, and Antonio Pierce and Jay Alford had one apiece.

The Giants’ secondary gave up one big play, a 45-yard touchdown pass, but it was more a fluke than a coverage breakdown: Bulger threw a deep pass to wide receiver Torry Holt, and although safety Kenny Phillips was in good position and got his hands on the ball, he bobbled it and it somehow landed in Holt’s hands while he was on his back in the end zone. Other than that play, the Rams never even got inside the Giants’ 30-yard line, and the only other points St. Louis scored came on a pair of 54-yard field goals from Josh Brown.

After Tuck, the Giants’ most impressive player was wide receiver Domenik Hixon, who caught three passes for 60 yards and was a demon on special teams, with a 50-yard punt return and two tackles on kickoffs. Big contributions from a little-known player like Hixon, who might not have made the Giants’ 53-man roster if wide receiver David Tyree were healthy, are a testament to the depth of the Giants’ roster.

The win improves the Giants’ record to 2-0 and means they will be tied with the winner of Monday night’s game between the Dallas Cowboys and Philadelphia Eagles for first place in the NFC East. With a fairly easy early schedule, there’s every reason to think the defending Super Bowl champions will remain in first place for, at least, the first couple of months of the season.

And the Giants should be a better team later in the season than they are right now. Manning is still working out the kinks with his receivers, and the defense is still breaking in five new starters. After a 2007 season in which the Giants were the unlikeliest of champions, in 2008 they’re looking like a team embarking on another march to the Super Bowl.