TUKWILA — Sounders FC coach Sigi Schmid has been on the end of an extraordinary comeback before.

The wrong end.

As coach of the Los Angeles Galaxy in 2003, Schmid saw a four-goal aggregate lead disappear to the San Jose Earthquakes in the second leg of the conference semifinals. So what's the takeaway eight years later, as his new team needs to erase a huge deficit?

"For me, it's just an example that everything's possible," Schmid said.

Possible, yes. But just barely.

The 2003 Earthquakes were the only team in MLS history to come back from down three goals or more in a two-leg playoff series. Trailing 3-0 to Real Salt Lake, Seattle hopes to become the second in Wednesday's 7 p.m. home leg of an aggregate-goals Western Conference semifinal.

"If we have the result we want to have, it'll be a game that people remember for a long, long time," said Schmid. "That's our objective, to create a game you're not going to forget."

The Sounders need a three-goal win after 90 minutes at CenturyLink Field to send the series to overtime. A four-goal win would advance Seattle to the conference final for the first time in franchise history.

So how does one go about such an immense comeback?

"You start by getting the first goal and go from there," said goalkeeper Kasey Keller. "Let them worry a little bit as the second and third ones come, but you can only get the second one after the first."

Schmid wants his team to be aggressive in pursuit of an early goal, but also smart.

"We don't want to be like a kamikaze," he said, "and run into an open knife by throwing everything forward trying to get the first goal in the first 10 minutes of the game and then take one on the other end of the field."

The Sounders have won three MLS games by three goals or more this season. Conversely, RSL has lost three MLS games by three goals or more since Sept. 24.

The biggest challenge for Seattle, however, is getting a lopsided result when the opponent knows exactly what to expect and protect against.

Though while the assumption might be that Salt Lake would bunker down and defend with all 11 players, coach Jason Kreis hinted he won't change the team's strategy.

"For me we've got to approach it as if we're 0-0 or maybe 1-0," Kreis told reporters this week.

Injuries will likely force some adjustments for both teams.

RSL center backs Jamison Olave and Nat Borchers, arguably the best defensive duo in the league, each were forced to leave Saturday's game with quadriceps injuries. The two traveled to Seattle, but are expected to be game-time decisions.

Salt Lake was 9-4-8 in the regular season when Olave and Borchers both started and 6-7 when one or both didn't play.

On the other side, Sounders FC midfielder Mauro Rosales, the team's assist leader, was ruled out of Wednesday's game due to the right MCL sprain he suffered in the regular-season finale Oct. 22.

Without him, Seattle didn't even record a single shot on goal Saturday.

"We can't change our performance from that night because it's not going to change that result," said Schmid. "What we can do is change our performance and affect the result (Wednesday) night, and that's our intention and that's our goal."

NOTES

• The draw for the CONCACAF Champions League knockout stages will be Nov. 8. Sounders FC advanced to the quarterfinals by earning a second-place finish in CCL's Group D.

• If the teams are tied on aggregate goals after 90 minutes Wednesday, they will play 30 minutes of overtime. If a winner still isn't determined, the series will be decided by a penalty-kick shootout.

Joshua Mayers: 206-464-3184 or jmayers@seattletimes.com