The Ravens have won 23 of their last 24 games at M&T Bank Stadium.
So who was the one?
None other than the rival Pittsburgh Steelers, who blindsided the Ravens on Dec. 5, 2010 with a blitz by safety Troy Polamalu.
The man nicknamed "The Flying Hawaiian" sack/stripped Ravens quarterback Joe Flacco in the fourth quarter, leading to a Steelers touchdown and a 13-10 Ravens loss. Had the Ravens won that game, they would have won the AFC North crown that season.
Since that painful loss, Ravens fans have left M&T Bank Stadium 15 straight times with smiles on their faces. It's the longest home winning streak in the NFL.
Outside linebacker Terrell Suggs was asked whether the fact that the Steelers were the last team to beat the Ravens at home provides any motivation for this Sunday's game.
"Thank you," he said with a wily grin. "I didn't know that, but we do now."
"That's first and foremost; defend M&T [Bank Stadium]. She's been mother to us all and been very good to us. So, we've got to continue to be good for her."
The Ravens frequently talk about their home atmosphere and Head Coach John Harbaugh has referred to the fans as being a wall of purple.
In October, ESPN declared M&T Bank Stadium the toughest NFL venue after polling more than two dozen NFL players, owners, general managers, scouts, analysts and writers.
"We take pride in it," Harbaugh said. "We're very proud of our fans. We are very proud of our city and very proud of the environment of our stadium, and our guys really like playing there."
The Ravens have a 32-5 record (.865 winning percentage) at home during the Harbaugh era. It's tied for the best mark in the NFL since 2008 with the New England Patriots.
Defending the home turf hasn't always come easy, especially this season, however.
The Ravens came back against New England to win by one point in Week 3. Baltimore survived three passes to the end zone at the end of the Week 4 Browns game, and hung on to win by seven. They watched a 51-yard field goal sail wide to cling to a one-point win over Dallas in Week 6.
"We've had some battles here. We've had a lot of battles," running back Ray Rice said. "We have won a few games on the road this year, but our best football is at home."
The last time the Steelers came to Baltimore was to kick off the 2011 season, Baltimore laid a 35-7 beating on them. Both meetings since have been three-point victories for the Ravens.
This Sunday, the man who caused the last loss – Polamalu – is expected to be back on the field for the first time since Week 5. Tight end Ed Dickson called Polamalu a "game-changer." Rice said he's relying on the fans to help.
"Being at home definitely helps when you have a team like the Pittsburgh Steelers coming in, because our fans are getting loud and getting into it," he said.
While crowd noise is definitely a factor at M&T Bank Stadium, which sells out for every home game, Steelers Head Coach Mike Tomlin didn't think that's what mostly makes the Ravens a challenge at home.
"They are a good football team. I think it starts there," Tomlin told the Baltimore media. "Obviously, the crowd is a factor – a positive one. But more than anything, they consistently put together good football teams. That's what makes them tough to beat at home."
Rice said "home dominance" is something Ray Lewis frequently preaches. It can often be heard in the pregame speeches he gives the team, which are broadcast for the entire stadium minutes before kickoff.
"You just aren't going to let somebody come into your home and let them walk all over you, especially without putting up a fight," Rice said. "This is our home. This is Baltimore. These are our fans. This is our city, and we want to do the right thing and go out there and play as hard as we can to protect our house."