Martin Havlat, Ryane Clowe and Joe Pavelski scored for the Sharks, who fell into 10th place in the Western Conference and fourth place in the Pacific Division, but remained just a point behind Dallas, Phoenix and Colorado in the ever-so-tight playoff race.
The Ducks remained in 12th place in the West with 73 points.
"Our team's got a lot of pride and we've played awfully hard from January," Ducks coach Bruce Boudreau said. "Whenever you can sort of derail, a little bit, a California team, you like to do it."
The Ducks beat San Jose for the fourth time in five meetings this season with one game left in the series. They're 3-0 at HP Pavilion, and Monday's win came against a Sharks' team that had won two straight and earned points in six of seven games.
"It was frustrating," Sharks forward Ryane Clowe said. "It was just a lack of intensity. It looked like we came out pretty good and then it was just disappointing to have the opportunity we had tonight to take a lead in our division and move into third place. That's a great opportunity. You just shake your head a little bit and wonder what happened."
Sharks goaltender Antti Niemi made his 11th straight start, but his hot streak came to a nasty end. Niemi gave up four goals on 26 shots and was pulled at 10:23 of the second period for backup Thomas Greiss after Guenin beat him on a one-timer from the blue line. Greiss allowed just one goal on 14 shots.
By the end of the second, the Ducks, who were coming off a loss Sunday night to Nashville, already had 34 shots and a 5-3 lead.
Sharks coach Todd McLellan said you "can't pin" this loss on Niemi. He pointed the finger at the Sharks in front of the goaltender, who gave up breakaways and sent the Ducks on power plays.
"Disappointed is a really good word," said McLellan, whose team faces the Kings in Los Angeles on Tuesday night. "The lack of energy and jump that we had as a team was baffling. It really was. When we're supposed to be as desperate as we are apparently. I can't figure out why we didn’t have that jump. Some nights when you don’t have it you have to rely on your hockey sense and your brain to put you in a position to be successful. We didn't have that going, either.
"We were the second-place team in a lot of areas tonight, and at the end of the night in the score, too. We looked unorganized. We weren't handling passes, so it made us slower. The frustration level went up. Just not a good night on our behalf."
Deslauriers allowed two goals on 28 shots in his other start, a 5-2 Ducks win over Dallas on Jan. 10. The Sharks had two goals on 14 shots in the first period and added another goal on seven shots in the second, but that was it.
"The good thing about not playing in a long time, you do a lot of practice time and do a lot of stuff in the gym," Deslauriers said. "Game-shape, I felt good out there. I wasn't out of breath or anything like that. It was more of playing the puck or getting (in synch with) the D-men, and obviously the shot doesn't come from the same angle in practice.
"They're a very skilled team with big-name forwards and D-men -- even the goalie -- and they're battling for the playoffs. So we knew they were coming hard. But we won tonight because the guys kept pushing. We responded to every push they made, and that’s why we won the game, because of the guys in front of me."
Ducks captain Ryan Getzlaf gave much of the credit for Monday's win to Deslauriers, who hadn't started a game in over two months.
"J.D. did what he needed to do tonight," Getzlaf said. "He made some stops at some key times and got a little active in the net. It was nice to see. He works in practice like no other. He's taken a lot of heat the last little while for shots in practice, but we were proud of him tonight."
After the Ducks and Sharks skated to a 2-2 tie in the first period, Anaheim outscored San Jose 3-1 in the second, building a two-goal lead.
The Ducks took advantage of a Sharks turnover to take a 3-2 lead on Perry's 35th goal of the season just 56 seconds into the second period. Joe Thornton sent a cross-ice pass above the Anaheim blue line that somehow got past wide-open Sharks defenseman Marc-Edouard Vlasic. The puck bounced off the lively new boards at HP and shot past Vlasic in the neutral zone to Getzlaf, who headed the other way on a breakaway.
"They were fortunate on that one," Vlasic said. "I was wide open. Jumbo made a great play. It just bounced right over, and with the new boards it went right to him."
Niemi stopped Getzlaf's shot from close range, but a hustling Perry was there to deposit the rebound in the net.
Guenin's laser, with Palmieri screening Niemi, put Anaheim up 4-2. But the Sharks cut the lead to 4-3 at 17:29 of the third on Pavelski's tip-in of Brent Burns' rocket from the blue line.
Thirty-three seconds later, Palmieri answered with his fourth goal of the season, getting his own rebound and beating Greiss with a sharp-angled low shot from right of the crease that snuck inside the post.
Palmieri, Bonino and Ryan played on a line together for the second straight game, and it appears as if Boudreau may have found something. They combined for two goals and six assists. Bonino had a career-high three points on three assists against the team that drafted him in 2007 then traded him to Anaheim in March 2009 before he ever played a game for the Sharks. Ryan had a three-point night with a goal and two assists. Palmieri had a goal and an assist.
"It's fun getting a win, but to do it against the Sharks is that much better," Bonino said.
Havlat gave the Sharks a 1-0 lead just 6:24 into the game on a power-play goal, knocking home a rebound in the blue paint after a Burns' blast. It was Havlat's third goal in three games since returning from hamstring surgery.
The Sharks' first lead lasted all of 51 seconds before Ryan tied it, ripping a rebound past Niemi. Palmieri earned an assist, darting through traffic to the crease and sending the puck toward Niemi. It bounced off Sharks defenseman Jason Demers' stick to Ryan, and he scored on a 15-foot slap shot. That was the first of two times the Ducks answered a San Jose goal with one of their own on the very next shift.
"It's a bad trend to get into," Thornton said. "We grabbed some momentum and the next shift they grabbed it right back."
Clowe put the Sharks ahead 2-1 at 9:20 of the first, scoring from the slot on a slick give-and-go with Havlat. Clowe fed Havlat in the left circle, got the puck back and snapped a 23-foot shot past Deslauriers.
San Jose's second lead of the night didn't last the rest of the period. With Burns in the penalty box for interference, Beauchemin scored a power play goal from just left of the crease at 17:52. Beauchemin took a pass from Bonino, who had chased down his own rebound near the boards behind the goal, and knocked the puck past Niemi.