Olave was originally injured in a Champions League match against Herediano on July 31.
He has played sparingly over the past three months, although he did enter Game 1 of the series against the Sounders in the 76th minute.
Prepared for Sounders' attack
Seattle attacked Real Salt Lake from the flanks in Game 1, and coach Jason Kreis expected the same tactic in the rematch.
"We need to be prepared for it because almost every team we play does that," Kreis said. "That's the space we give them."
Seattle had 30 open-play crosses in Game 1, although none of them led to a goal in the 0-0 standoff.
"In every soccer system," Kreis said, "there are spaces you allow [opponents] to play in and spaces that you do not. So, the last few years, we've had to deal with a lot of service into our box. But we think we have the right personnel to handle that."
RSL and Seattle played three straight scoreless draws heading into Game 2, including two during the regular season.
Kreis, however, was convinced both teams were capable of rallying in the event of falling behind.
"Oh, geez," he said. "These teams are both experienced enough and have played so many big games that I don't think the first goal holds as much weight as it does in a typical MLS [game]."
Smiling slightly, Kreis added, "In this series with these two teams I think you better be ready to play all 90 [minutes]. Or 120."
Galaxy await in conference finals
While Real Salt Lake and Seattle battled for a berth in the Western Conference finals, the Los Angeles Galaxy had already punched their ticket.
L.A. stunned top-seeded San Jose on Tuesday night, 3-1, in Game 2 of the other conference semifinal. The victory gave the Galaxy a 3-2 win in the aggregate.
Since 1996, Los Angeles has qualified for the conference finals 12 times. The Galaxy have reached the MLS Cup seven times.
In L.A.'s shocking win over San Jose in Game 2, Robbie Keane scored two goals, Mike Magee added another and Landon Donovan assisted twice.
The Earthquakes went 3-0-1 against the Galaxy during the regular season but had an 18-game home unbeaten streak snapped.