Seattle, Denver, New England and Kansas City remained unblemished.
The rest of the NFL remained unbelievable.
Cleveland beat Cincinnati? The Browns were supposed to be cooked a couple weeks ago when they traded running back Trent Richardson to Indianapolis and promoted third-string quarterback Brian Hoyer to starter. Now, they've won consecutive games and just knocked off the best team in the AFC North.
Pittsburgh is winless? Yes, the Steelers lost in London to Minnesota, 34-27. It was the first win of the season for the Vikings.
"We are in uncharted territories and the water is dangerous right now," Steelers quarterback Ben Roethlisberger said. "So we have to stick together and get out of it. Right now, you could say we're the worst team in the league. That hurts."
Not so fast. The New York Giants can stake their claim to that title. After Sunday's 31-7 defeat at Kansas City, one Giants player was feeling so adrift he even turned to reporters for a potential remedy.
"If y'all find some answers, let me know," defensive end Justin Tuck said to those gathered around his locker. "I'm willing to try anything and everything."
Anything and everything. That's an accurate description of what happened around the league in Week 4.
Detroit scored four touchdowns and four field goals against Chicago in a 40-32 victory over the Bears. Jay Cutler came into that game with a 7-1 record against the Lions and one interception in those eight games. Sunday, the Chicago quarterback had three interceptions and a fumble.
The Bears rallied down the stretch, but they could never fully recover from giving up so much ground in the first half, when they fell behind, 30-10.
"There are no moral victories, but I thought our guys played tough for the last 30 minutes of that game," Bears Coach Marc Trestman said.
No moral victories? There are certainly morale victories, and that's what San Diego accomplished by beating Dallas at home, 30-21. The Chargers, who typically fold like origami at the end of games, avoided fatal mistakes and outscored the Cowboys in the second half, 20-0.
Like the Chargers, Seattle was similarly, well, half-hearted.
After falling behind in the first two quarters, 20-3, the Seahawks shut down Houston in the second half and collected a major character-building victory. They are notoriously weaker on the road, and they were missing three starting offensive linemen — among them Pro Bowl left tackle Russell Okung and Pro Bowl center Max Unger — and yet Pete Carroll's players got the job done.
The touchdown that forced overtime was a 58-yard interception return by Seattle cornerback Richard Sherman.
Carroll said that on that pick-six "it was like the world stopped for a second there because he had the ball in his hands and no one in front of him, and we had practiced exactly that."
If practice makes perfect, Peyton Manning and the Broncos sure have practiced a lot. In blowing out Philadelphia, 52-20, Denver scored the most points in franchise history and pushed its regular-season winning streak to 15 games, each by at least a touchdown.
Seattle wasn't the only team to dig its way out of a double-digit deficit in the fourth quarter. So did Arizona in its 13-10 victory at Tampa Bay.
The Cardinals trailed, 10-0, in the fourth quarter before rallying. Patrick Peterson had two interceptions in the final period, the first setting up Carson Palmer's 13-yard touchdown pass to Larry Fitzgerald, and the second clinching the victory that sent the Buccaneers to 0-4.