It's all about familiarity.
"It took a while, but now we know how they play and that's what's made us better against them," Niemi said. "We're feeling comfortable when we face them."
Niemi made 20 saves and Joe Pavelski scored the first of three straight San Jose goals to lead the Sharks to a 4-2 victory Tuesday night. San Jose completed a season sweep of the Blues, winning all three games by a combined 16-7.
"It's really good to get the three wins against a tough team," Sharks coach Todd McLellan said. "A lot of different variables went into the three nights. Fortunately for us, we got the (six) points."
St. Louis, which got goals from Kevin Shattenkirk and Jay Bouwmeester, had won six of seven against San Jose entering this season. But the Sharks have turned it around, winning 6-3 and 6-2 in the first two meetings.
Niemi improved to 18-6-6. He held off the Blues when they had a 6-on-4 skating advantage in the closing 2 minutes.
"This was big for us," Niemi said. "We got in front, then reset our game and got the win."
The Blues were playing their third game in four nights. San Jose had been in St. Louis since Sunday after losing in Nashville on Saturday.
"They're a really good team and they could have been a little tired," Sharks center Joe Thornton said. "We started fast and we played good enough to win."
The Sharks jumped to a 2-0 first-period lead on goals by Pavelski and Irwin in a span of 2:56. Both came from close range on rebounds of missed shots that caromed off the end boards.
Pavelski scored his 13th after a miss by Havlat, and Irwin jumped on a misfire from Justin Braun for his first of the season.
St. Louis goalie Jaroslav Halak gave up three goals on the first 12 shots and fell to 16-6-2. Halak has allowed 14 goals in his last five starts, 10 in the first period.
"Tonight, it starts with me," he said. "I need to do a better job. We just need to play better, that's the bottom line."
The Blues climbed to 3-2 on Bouwmeester's goal with 24.2 seconds left in the second period, but Havlat pounced on a rebound with 11:41 left in the game to make it 4-2.
"The fourth one was tough. It was kind of like a dagger," Shattenkirk said. "Because we felt like we were moving in the right direction."
San Jose snapped a season-high, four-game road losing streak with a solid effort.
"A win is a win and we're going to take that," McLellan said. "I haven't seen anybody play a perfect game this year. We let the momentum get away on us. But in the third period, I thought we went out there and re-established it."
San Jose has outscored its opponents 44-15 in the first period this season. .... Blues coach Ken Hitchcock celebrated his 62nd birthday. ... St. Louis C David Backes missed his first game since Jan. 25, 2010, a string of 274 successive regular-season appearances. He sustained an upper-body injury in a collision with Ottawa C Colin Greening on Monday. Backes, who has 16 goals and 14 assists in 32 games, is expected to be out at least a week. ... The Blues were also without LWs Jaden Schwartz and Vladimir Sobotka, who missed the game with upper-body injuries. Backes, Schwartz and Sobotka have combined for 29 goals and 38 assists. ... The Sharks are 0 for 16 on the power play over their last seven road games.