Saints quarterback Aaron Brooks was sacked three times in the first quarter. The big one was by rookie end-linebacker Kalimba Edwards, who jarred the ball loose from Brooks and end James Hall recovered the fumble and returned it 22 yards for a touchdown, giving the Lions a 10-0 lead.
Detroit's Desmond Howard set the tempo, returning the the game's opening kickoff 70 yards to the New Orleans 22 and setting up Hansen for a 23-yard field goal.
"They played a great game from the first snap to the last snap," said Lions coach Marty Mornhinweg, who won for just the third time in 20 games. "This football team had to play almost perfect to beat that team. Our defense came up big to force those turnovers and the special teams were huge too."
Harrington connected with Bill Schroeder on a 38-yard touchdown to increase the lead to 20-0 with 4:53 left in the second quarter.
He did not turn the ball over in his second NFL start after throwing four interceptions in his debut last week.
"This speaks volumes to the character of this football team," Harrington said. "I told them all week that winning is not a goal. Winning is a result of being prepared, executing the game plan and then having the attitude and the confidence that no one is going to stop us from winning the football game. We built that up last week and capitalized on it this week."
"It's hard to rate his leadership after only two games, but he has handled virtually every situation, crucial situations, and handled them beautifully," Mornhinweg added.
The Saints trailed 20-0 for the second straight week but were unable to overcome the deficit the way they did at Chicago last week.
"I say last week we got lucky, to be down 20-0 in a football game in the NFL and come back," Brooks said. "Now this week we're down again and it goes to show you, you can't expect to be down by a lot of points and expect to win. It's a tough loss, but at the same time it's going to be a wakeup call for a lot of players and coaches here."
Brooks hooked up with Jerome Pathon for a six-yard touchdown with 3:45 remaining in the game to pull the Saints within 26-21, but were unable to get the ball back. Brooks was 27 of 48 for 269 yards and two scores, but was picked off twice.
"In this league, all the teams are good," Saints Coach Jim Haslett said. "I'm not going to say it's a letdown, but we didn't play well for whatever reason. Their team played extremely well, they had a good game plan. It's hard to win games when you get behind in this league."
Hanson kicked a 38-yard field goal early in the fourth quarter to extend the Lions' lead to 26-15.
Deuce McAllister rushed 12 times for 61 yards and caught eight passes for 67 yards for New Orleans.
The Saints played the final quarter without receivers Joe Horn, who left with a knee injury, and rookie Donte' Stallworth, who left with a hamstring injury.
Stallworth caught a touchdown pass in his fourth straight game -- a four-yard reception with 1:25 left in the first half. Charlie Brown holds the record with a touchdown catch in his first five games for the Washington Redskins in 1982.