Evgeni Nabokov earned his NHL-best 43rd victory for the Sharks, whose remarkable third-period defense put them seven points ahead of second-place Anaheim in the three-team race for the Pacific title. After Roenick put San Jose ahead early in the third period, the Ducks never tested Nabokov again.
The Sharks' 14th win in 15 games vaulted them seven points ahead of Anaheim and 10 in front of the third-place Dallas Stars.
Todd Marchant scored and Jonas Hiller made 41 saves for the defending Stanley Cup champions, who finished with just 13 shots -- one higher than their franchise-record low. Anaheim had been held without a shot in just one previous period in club history: the first period against Dallas on Dec. 27, 2000.
Both teams entered the game on prolonged winning runs, with Anaheim losing just four times since Feb. 5 and San Jose earning 27 points in its last 14 games.
San Jose trailed Anaheim and Dallas for most of the season before vaulting into first place with 11 straight wins. Though a division title means little in the postseason, a second-place finish in the overall Western Conference standings would be particularly desirable for any of the three contenders behind Detroit -- since the two teams that don't win the title are likely to play each other in the first round.
The Sharks, who outshot the Ducks 43-13, also surmounted a mental block one week before finishing their always-intense season series against Anaheim, which had won five of the clubs' first six meetings this season, including all three trips to the Shark Tank. The Ducks had won six straight overall in San Jose, tying the club record for consecutive road wins against one team.
San Jose got rolling 40 seconds in when Thornton's top line forced a turnover. Milan Michalek made a sharp pass across the crease to Thornton, who sidestepped Scott Niedermayer and backhanded in his 21st goal.
The Ducks evened it early in the second when Chris Kunitz found Marchant across the ice for his ninth goal. The Sharks failed to convert on two minutes of 5-on-3 play late in the period when Todd Bertuzzi and Mathieu Schneider were called for simultaneous penalties.
San Jose got another 102 seconds of 5-on-3 advantage early in the third when Travis Moen shot the puck into the stands while killing a penalty. Roenick didn't waste it, putting a short shot through Hiller's pads for his 13th goal. Roenick's second in two games was the 508th of his career, passing Jean Beliveau for 36th place in NHL history.
The Sharks usually were in control of the puck during the third period. Anaheim's frustration showed when Kunitz took a cheap-shot hit at Jonathan Cheechoo at mid-ice with 90 seconds to play, but wasn't penalized.
The clubs finish the season series next Friday at Anaheim. Notes:@ Cheechoo finished with nine shots. ... Sharks rookie Torrey Mitchell won't be suspended for his collision with Minnesota D Kurtis Foster on Wednesday night. Foster broke his left leg while running into the boards in a race with Mitchell. ... With Chris Pronger sidelined by a suspension, the Shark Tank faithful turned their nonstop displeasure on former San Jose forward Teemu Selanne, booing the Finnish Flash every time he touched the puck. ... The game was briefly delayed midway through the third when Cheechoo's slap shot hit Hiller squarely in the head, dropping the goalie to the ice in pain. Hiller kept playing after getting a bandage on his right temple.