It was Lalas whose overtime goal knocked the Fire out of the U.S. Open Cup semifinals in August and prompted that memorable celebratory run up an ivy-covered slope at Cal State Fullerton's Titan Stadium.
So what will it take?
"I think it's a combination of things that we've had throughout the year, whether it's moments of brilliance coming from unlikely sources or a little bit of luck," Lalas said Tuesday.
"I also think the mentality we've possessed from the start in terms of really believing we could win is something that's gotten us through in games where things haven't gone well. That's real important."
Important, too, is the return of Mexican striker Luis Hernandez to the Galaxy's starting lineup after being limited by injury to only 31 minutes in the three-game quarterfinal series victory over the New York/New Jersey MetroStars.
Brilliance, luck and self-belief are all very well, but the Galaxy still must overcome Chicago's home-field advantage. Game 2 is Saturday at Fullerton, but Game 3, if necessary, will be back here in one week's time, and the Fire was 11-2-3 at home this season, including two quarterfinal playoff victories against the Dallas Burn.
Then there is Peter Nowak, the Polish playmaker who has led the Fire for four seasons and is a significant threat on offense.
"He's not only a quality player, he's also their emotional leader, he's the engine for their team," Galaxy Coach Sigi Schmid said. "I have a tremendous amount of respect for Peter. I don't know if you can ever stop Peter, but certainly we've got to keep him in check."
One of those who will be trying to do so is midfielder Simon Elliott.
"If he hasn't got the ball, it's hard for him to do anything, isn't it?" Elliott said, suggesting one way to manage the task. "I think he's the best player in the league, along with [D.C. United's Jaime] Moreno, so he's going to be hard to stop. He's a guy we're going to have to watch for sure."
Like Lalas, Schmid has his own theories on what it will take to win the series.
"To beat Chicago you have to be very alert mentally," he said. "You have to be constantly aware of situations because they're a battling team, and you've got to move the ball quickly on offense because they're a team that closes things down very well defensively."
Rain, an old Galaxy nemesis, is forecast for today.
"It's going to impact the play," Galaxy goalkeeper Kevin Hartman said. "It's going to be more of a long-ball game; it won't be quite as easy for people to build up [attacks on the ground] because of the difficulty of trapping the ball [in wet conditions]."
The weather is the least of Schmid's concerns.
"It just makes it a more roll-up-your-sleeves game," he said. "I think Chicago is a team that has a lot of character and has a lot of fighting ability and desire and effort that they put into their game. If it rains and it turns into that kind of a game, they have the people who will battle and scrap for everything.
"We showed in the New York series that we have the same capability."