SAN JOSE -- The San Jose Sharks are known for their fast starts at SAP Center, where they've made a habit of overwhelming opponents in the first period.

But when the puck dropped Saturday night for Game 5 of their Western Conference First Round series against the Los Angeles Kings, it was as if the Sharks were skating in quicksand and the Kings on lightning-fast ice.

The Kings bolted to a 2-0 first-period lead on goals by Tyler Toffoli and Anze Kopitar. They added a power-play goal 22 seconds into the second period when Jeff Carter scored and cruised to a 3-0 victory, cutting the Sharks lead to 3-2 in the best-of-7 series with Game 6 set for Monday night at Staples Center (10 p.m. ET; NBCSN, CBC, RDS, CSN-CA, PRIME).

"Usually we have really fast starts in this building and that wasn't the case tonight," Sharks captain Joe Thornton said. "They started faster than us. Really, it's a rarity around here. We just have to have better starts. That's the bottom line. Last two games we haven't had very good starts."

The Sharks were outshot 18-6 in the first period and had had 10 giveaways to four for Los Angeles. The Sharks had hoped to generate a better forecheck and put more pressure on Kings goaltender Jonathan Quick, but they had trouble even getting the puck out of their own end.

"I don't have an explanation for that," Sharks coach Todd McLellan said of the sloppy play. "I thought we were slow. Simply put we were slow. We didn't have legs and we didn't execute well, which made us even slower. We had poor puck support, and that made us slow."

McLellan pulled starting goaltender Antti Niemi after Carter's goal and replaced him with Alex Stalock for the second straight game. Niemi was pulled in Game 5 after giving up his fifth goal on 26 shots 34 seconds into the third period. This time Niemi was replaced after giving up his third goal on 19 shots.

McLellan was asked if he had a decision to make for Game 6.

"Yup. Just like any other night," McLellan said. "We have two good goaltenders. We'll have to make some decisions throughout our lineup at every position because we weren't obviously near good enough tonight."

McLellan started juggling his lines in the first period, searching for combinations that would spark his team. No luck.

"The (original) plan went out the window four shifts in when we were standing, still watching," McLellan said. "There wasn't one line combination that stayed the same throughout the first 30 minutes of the game. Trying to find legs, trying to find pairs of players that were capable of executing, trying to find momentum. ... It was a bit of desperation trying to find pairs."

Sharks forward Joe Pavelski had no explanation for his team's poor start.

"The plan was to start fast, get it in, simplify, win the faceoffs, get in on the forecheck -- all those sorts of things," Pavelski said. "It didn't really happen. It's tough. You fall behind early, you have to play catch-up and then we got into penalty trouble."

After scoring the first goal in Game 1, the Sharks have given up the first goal in each of the next four games.

The Sharks were forced to play with five defensemen for most of the game after Marc-Edouard Vlasic was injured with 5:51 left in the first period after being checked into the board by the Kings' Jarret Stoll and, according to McLellan, taking a "blow to the head."

Defenseman Dan Boyle was in no mood to analyze the loss.

"We lost. On to the next game," a clearly upset Boyle said. "I know you guys want to dissect it and I'm usually pretty good with you guys answering questions, but this is a series, and that's why this is a best out of seven.

"We didn't win the game. You can blame a lot of different things, but we've got to turn the page and move on. Winning teams do that, and we will do that."

After took a 3-0 lead in the series, the Sharks have lost two straight games, but McLellan said his team did not become "lackadaisical or overconfident" after building a big cushion.

"No, I don't think we approached the game that way," McLellan said. "You have to have your tools in your tool box to be successful, and we didn't . Our team game -- and we saw it through the first little bit -- is when we play with some tempo and some speed. For whatever reason we were sluggish, mentally and physically. That doesn't get us wins."