The festive occasion was made complete by a few familiar friends: Rex Ryan and the Baltimore defense.
Flacco ran for a 38-yard touchdown in his first NFL start, and the Ravens held the Cincinnati Bengals to 154 yards and eight first downs Sunday in a 17-10 victory.
"It's a thrill," Harbaugh said. "I'm appreciative of [owner] Steve Bisciotti, [general manager] Ozzie Newsome and the rest of the Ravens organization for giving a no-name a chance to be a head coach in this league. We have a long way to go, but this is a good start."
Thrust into a starting role because of a season-ending shoulder injury to Kyle Boller and Troy Smith's infected tonsils, Flacco deftly operated within the system of new offensive coordinator Cam Cameron. The rookie went 15-for-29 for 129 yards and no interceptions, and his touchdown run put Baltimore (1-0) up 17-3 in the third quarter.
"This is just a beginning for Joe," Harbaugh said.
If Flacco was unnerved playing in his first NFL game, he sure didn't look like it. Or feel like it.
"It's just football. It's a lot of fun, though, just like it's always been," said Flacco, the 18th overall pick in the NFL draft. "I think our offense was in control all day. And obviously we had a lot of help from our defense."
Ryan, retained as defensive coordinator when Harbaugh replaced Brian Billick, put together a game plan that rendered the Cincinnati offense helpless. Chris Perry gained 37 yards on 18 carries and Carson Palmer was 10-for-25 for 99 yards and an interception.
Chad Ocho Cinco, forced by the NFL to wear Chad Johnson on his jersey, was held to one catch for 22 yards. He praised the blitz-oriented defense deployed by Ryan.
"Two thumbs up to him and what they did today. It was unbelievable, and I told him after the game," Ocho Cinco said. "I don't know what they were playing. That's some playground defense."
Cincinnati's lone touchdown came on a 65-yard fumble return by Johnathan Joseph. Palmer couldn't take the Bengals (0-1) closer than the Baltimore 17, and that drive ended with an interception.
"We got outplayed," he said. "It was just an ugly game offensively. When you score three points, it's never good. And our three points were on a two-minute drive. It's a sick feeling, and it's going to feel even sicker when we watch the film."
Flacco's touchdown run, which came on a rollout to his right, was 13 yards farther than his longest run at the University of Delaware. Baltimore's other touchdown came on a double reverse, a trick play that represented a marked departure from the conservative offense employed by Billick.
After Joseph's return of a fumble by rookie Ray Rice made it 17-10 with 10:15 left, the Bengals faced a fourth-and-1 at the Baltimore 25. Perry ran into Haloti Ngata for a 1-yard loss, and Baltimore held the ball the rest of way.
"Either they drive you back or you drive them back," Ngata said. "That time I made the play."
On Baltimore's final drive, Le'Ron McClain ran for 40 yards. He finished with 86 yards rushing; he had 18 as a rookie fullback last year.
"I'm a fullback first, running back second," he said.
Cincinnati's only points in the first half came on a 43-yard field goal by Shayne Graham with five seconds left that made it 10-3.
Ravens tight end Todd Heap lost a fumble on the second play from scrimmage, but Cincinnati failed to capitalize. On the Bengals' second series, a pass deflected off the hands of Ocho Cinco was tipped and intercepted by Chris McAlister.
The Ravens then moved 78 yards, the last 42 on the surprising double reverse. After Flacco handed off to Derrick Mason, who was running around right end, Mason flipped the ball to Mark Clayton running the other way. Clayton weaved into the end zone for a 7-0 lead.
Late in the half, McAlister recovered a fumble by Perry at the Cincinnati 40 to set up a field goal by Matt Stover.
Ocho Cinco has at least one catch in 93 straight games, tying the team record set by Carl Pickens. ... Baltimore has gone an NFL-best 20 straight games without allowing a 100-yard rusher. ... Cincinnati was denied its fourth straight season-opening win.