The Sabres tied the game within four minutes of Sherwood's goal, on the strength of a power-play marker from Okposo and Jeff Skinner's fourth goal in as many periods. Rasmus Ristolainen added another in the third period, which stood as the game-winner in a 4-2 victory.
Buffalo stayed the course all the way through to the final minute, when Johan Larsson snatched the puck away from the goal line to prevent a tying goal and Patrik Berglund scored into an empty net with 16.1 on the clock.
Video: Ristolainen pots game-winner as Sabres top Ducks
With the win, the Sabres pulled to 5-4-0 on the season and finished their West Coast trip with six of an available 10 points. They did it with arguably their two best performances of the season, on back-to-back days no less.
"Two complete games that we just played," Okposo said. "I thought that that was the first time all year that we got down in a game and we never changed the way that we played. That second goal could've been a back-breaker for us. We just stuck with it. We played the exact same way and we got rewarded."
The Sabres held a 24-17 advantage in shots at the time of Sherwood's goal, which came directly on the heels of a long possession in the Anaheim zone. They outplayed the Ducks in the first period, too, but trailed after Sam Steel had a shot deflect in off his body past Carter Hutton.
Going back to last season - and as recently as their loss in San Jose on Thursday - Sabres coach Phil Housley has preached the importance of staying the course through adversity as being a key lesson for a young team learning to win.
In the past, the Sabres may have responded to Sherwood's goal by trying to do too much and turning the puck over in the process. In this instance, they stuck with what worked. They peppered Ryan Miller with a season-high 45 shots and finished with a 71-43 edge in shot attempts, both indicators of how much time they spent in the offensive zone.
"They obviously deserved to win this game, just the way they played," Housley said. "But I think it's a credit to our leadership group who are keeping our guys together and keeping them as a tight group. They talk a lot in that room, they say the right things and they're leading by example.
"It's a feather in their cap, the way they've worked, especially being down 2-0 in a tough building. They just kept working."
It was clear in their responses. The Sabres drew penalties within a minute of both Ducks goals. The first power play was unsuccessful; the second led to Okposo's goal.
They'll return to Buffalo with 10 points, two back from division-leading Toronto, with a template for success moving forward.
"That's what happens," Okposo said. "I think when you look at the really good teams around the league, that's what they do. They just play the same way all the time. We're trying to learn that. We're trying to get there. I think the more we have games like this, the more we can stick together, the better we'll be."
Skinner's big trip
Coming off a performance against Los Angeles in which they tallied a combined nine points, the trio of Skinner, Jack Eichel and Jason Pominville were dominant once again, beginning with their first shift of the night. Skinner tallied five shot attempts in the first period, four of which went on goal.
They were finally rewarded with 2:29 remaining in the second, when Eichel made a no-look pass from along the boards to spring Pominville and Skinner free for a 2-on-1 rush. Pominville got the pass across and Skinner beat Miller off his backhand.
Video: BUF@ANA: Skinner backhands puck past Miller
Afterward, in the visiting dressing room at Honda Center, Skinner glanced two stalls down toward Eichel and said what everyone else was thinking.
"I wouldn't say it to his face, but I think not many players in this league can make that play," he said. "That's all. It's an unbelievable play on the wall. Pommer does a great job getting it over the guy's stick and giving me a little bit of a break. I was happy I was able to put it in, because those were two pretty good plays."
It was a pretty good trip for Skinner, too. He scored seven points (5+2) in five games, including a hat trick against the Kings.
Okposo scores his first
The effect of Okposo's goal was a weight lifted in multiple senses. It was Buffalo's first goal of the night, sure, but it was also Okposo's first of the season. The forward entered the game without a goal despite ranking third on the team with 19 shots.
"That was huge," Skinner said. "Okie's had a bunch of chances, it was nice to see him get one there. It was a huge lift for us."
The play began when Evan Rodrigues passed low to Sam Reinhart, stationed to the left of the net. Okposo came dashing down the right-wing side, and Reinhart hit him with a pass through the crease.
Video: BUF@ANA: Okposo finishes passing sequence for PPG
"It was just a good play," Okposo said. "I'm just trying to get down on the back side, and that seam was there. Rhino's going to hit me there every time."
Keeping it simple
It was a big rebound game for the Buffalo power play, which was 0-or-12 in three games entering Sunday. Players agreed that the fix would be simply getting more shots to the net, and that's exactly what happened on Ristolainen's go-ahead goal.
The defenseman took a slap shot from the point with Reinhart planted in front of Miller, taking away the goalie's line of sight.
Video: BUF@ANA: Ristolainen nets PPG to put Sabres ahead
"I saw short-side open," Ristolainen said. "That's usually what the net-front guys do. They take the goalie's eyes away and leave you either side open. Look what happened."
Larsson, Berglund close it out
Housley said he felt he could trust the line of Zemgus Girgensons, Larsson and Berglund in any situation prior to putting them together against Los Angeles, and boy did he mean it. The trio was on the ice to start each of the past two wins, and they finished it in Anaheim.
Larsson saved the game after the puck trickled past Hutton in the final minute, with the Ducks utilizing the extra attacker. He got his stick on it just as it neared the goal line and swung it out of harm's way.
Video: BUF@ANA: Hutton makes flurry of saves late in the 3rd
Larsson finished the game with 13:51 of ice time, including 3:10 shorthanded, another bounce-back performance from a player who began the season injured and had been a healthy scratch for three games entering Saturday.
"I feel good," he said. "It's always tough to sit out, obviously, but I was confident. I was injured, coming back from injury. I'm confident in my game. Phil knows what kind of player I am. The L.A game felt good and it just carried over from there."
"I'm really happy for him," Ristolainen added. "It's tough to see a really good friend being out of the lineup and injured early in the year. The way he played last two games, he's working really hard, grinding night in, night out, giving everything for the team. It's good to see him contributing."
Berglund had also been a healthy scratch prior to returning against the Kings. His empty-net goal was his first as a Sabre.
"That line's played terrific over the last two games," Housley said. "You can count on them in a D-zone draw, killing penalties, blocking shots and helping out down low at our net-front. It was good to see Bergy get one, because they deserved it."
Zach Bogosian extended his fight streak to three games with a quick takedown of Ducks forward Ryan Kesler in the second period. Bogosian fought Joakim Ryan at the end of Thursday's game in San Jose and threw hands with Kyle Clifford in Los Angeles on Saturday.
Bogosian's already matched his career-high for fights in a single season, according to hockeyfights.com.
The Sabres return to KeyBank Center to host the Montreal Canadiens on Thursday. Coverage on MSG-B begins at 6:30 p.m. with the GMC Game Night Pregame Show, or you can listen live on WGR 550. The puck drops at 7.