LOS ANGELES (AP) -- Even with just 20 minutes separating the Los Angeles Kings from a perilous elimination game in St. Louis, their dressing room was calm and cool.
Anze Kopitar wasn't surprised. After all, the Kings didn't win the Stanley Cup last year by panicking over a little trouble.
Kopitar tied it with 12:46 to play, Justin Williams tipped home the go-ahead goal 76 seconds later, and the Kings evened their first-round series with a 4-3 victory over the Blues on Monday night.
Jeff Carter and Dustin Penner also scored for the defending NHL champions, who responded to a late deficit with the same tenacity that made them champions. After four games of a remarkably even series, these two teams are level again.
"The resilience of our team is amazing," said Kopitar, who ended a personal 19-game goal drought after a slick pass from captain Dustin Brown. "To keep coming back and coming back like that, it's incredible. To be down 2-0, and then down 3-2 in the third period, it shows what we're capable of overcoming."
Mike Richards had two assists for Los Angeles, which dropped the first two games of the series in St. Louis and barely survived for a 1-0 victory in Game 3. The Kings erased an early two-goal deficit and a third-period deficit in Game 4 to earn their ninth consecutive home victory since March 23.
"That's playoffs," Williams said. "That's battling all the way to the final buzzer. We needed a big third period, and we responded. We're an experience team. We've been through a lot, and we knew we were facing a daunting task going back to St. Louis down 3-1, and we found it in ourselves. This is a group that's been in pressure situations before, and we know what we have to do to overcome it."
Game 5 is Wednesday in St. Louis, with Game 6 back at Staples Center on Friday.
T.J. Oshie scored his first two playoff goals for the Blues, who had the champs on the brink of serious trouble before Kopitar and Williams beat Brian Elliott, who stopped 25 shots.
"It's a worst-case scenario when you (lose) a two-goal lead," said Blues captain David Backes, who scored 1:12 into the game. "They had their fans behind them, but we've still got a lot more in the tank, and we're going to find it. It's just a matter of 20 guys staying on the same page."
The Kings hadn't won a playoff game after trailing by two goals since 2001, and they hadn't rallied from a third-period deficit to win a postseason game since the first round last year.
The Blues tried to protect a late lead in front of a raucous Los Angeles crowd, but they couldn't stop Kopitar, Los Angeles' perennial scoring leader. The Slovenian forward hadn't found the net since March 25, and acknowledged the struggle was weighing on him - but he gave Elliott no chance on his shot in front.
Moments later, Williams slipped in front of Elliott and expertly tipped home Richards' shot from the boards. A video review couldn't conclusively determine whether Williams' stick had been illegally high.
"You play all of last season and all of this season to build confidence in yourselves for situations like this," Richards said. "They've got a great team over there, and there's a lot of similarities between us. It's the smallest things that make the difference, and we had some success tonight."
Jonathan Quick was seriously tested in the final seconds after St. Louis pulled Elliott for an extra attacker, but he finished up his 19-save performance as the sellout Staples Center crowd waved white towels to celebrate another gritty postseason win.
"They took the game to another level tonight, and we didn't have an answer," Blues coach Ken Hitchcock said. "We made two mistakes, two really poor mistakes to give them odd-man rushes to get them back in the game, but even when it was 3-2, they were playing better than we were. ... We didn't manage the puck very well in the second and third period really at all, and paid for it dearly."
Both teams struggled offensively during the first three games, never leading by more than a goal. After the Blues' identical 2-1 victories at home, Quick posted his fifth career playoff shutout in Game 3.
But the Blues and Kings scored four goals in the first 14 1/2 minutes of Game 4 and combined for seven goals - the same number they scored in the first three games of the defense-dominated series combined.
That offensive struggle disappeared 72 seconds into Game 4, when Los Angeles left Backes unchecked as he put a wide rebound off the end boards into Quick's unguarded net for his first goal of the series. Just 3:20 later, Oshie deflected Kevin Shattenkirk's shot in front of Quick for his first goal in 17 career playoff games.
Staples Center fell silent after the Blues took the first multigoal lead of the series, but the Kings swiftly answered.
Richards got the puck along the boards and found his good friend Carter in front for a quick goal midway through the period. Carter led the Western Conference with 26 goals in the regular season, but had managed just nine shots and a minus-2 rating in the first three games.
The Kings evened it with a 3-on-1 finished by Penner. The two-time Stanley Cup winner got his first playoff goal since his overtime winner to end last season's Western Conference finals in Phoenix.
Oshie put the Blues back ahead shortly after a second-period timeout, sending a rebound of Vladimir Sobotka's shot over a prone Quick at a sharp angle.
NOTES: Blues F Vladimir Tarasenko made his NHL playoff debut, replacing Adam Cracknell on the fourth line. Cracknell hadn't been playing extensively for St. Louis, and Hitchcock wanted better offensive skill in the lineup after several missed scoring opportunities in Game 3. ... Los Angeles dressed seven defensemen for the second straight game, sitting forwards Jordan Nolan and Brad Richardson in favor of Alec Martinez, who picked up an assist in both games. ... The NHL announced Los Angeles will host the Anaheim Ducks at Dodger Stadium on Jan. 25.