A 3-1 defeat at home to Necaxa dropped the Sounders down to second in the West 6 standings, while LA were first in West 2 following a shootout victory over Guadalajara (5-4).
Match preview
By the skin of their teeth, Seattle are through to the knockout phase of this competition, finishing above Minnesota United on goal difference.
Despite going in front after eight minutes on Sunday, the Rave Green failed to hold it together, losing for the third time this season in all competitions when netting first.
For a side that have been among the best defensively in Major League Soccer this year, conceding the second-fewest goals (29), they have not been quite as sharp in recent outings, allowing three goals in two of their previous three competitive fixtures.
Their defensive record in this competition is not great either, with Seattle conceding 13 goals in their last five Leagues Cup contests.
The only three victories for Brian Schmetzer's men at this tournament occurred when they were ahead or level at the interval, though they have also lost three times when tied after 45 minutes.
Thursday will be the first time they battle an American opponent on home soil in the Leagues Cup, with their only previous game at this tournament against an MLS side ending in a 3-0 loss at Real Salt Lake last year.
More often than not this season, the scoring depth of the Galaxy has carried them through, and that was the case in their Leagues Cup group stage, as their four goals came from four different players.
Greg Vanney's men are unbeaten in their last four matches across all competitions, netting multiple times in each of those instances.
Their only Leagues Cup victory away from Dignity Health Sports Park occurred in their opening game against the San Jose Earthquakes (2-1), while Thursday will be the first time they play a match in this tournament outside California.
The Galaxy are undefeated in 2024 when scoring multiple times, netting the joint-second most goals in the MLS Western Conference this year alongside the Colorado Rapids (50).
Over the 2024 domestic campaign, LA have collected five points away from home when conceding the opening goal, though they lost their last road game versus an MLS opponent 2-0 at Dallas.
They are winless in nine successive visits to Lumen Field with their last victory in Seattle occurring during the 2016 MLS regular season (1-0).
Seattle Sounders Leagues Cup form:
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Seattle Sounders form (all competitions):
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Los Angeles Galaxy Leagues Cup form:
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Los Angeles Galaxy form (all competitions):
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Team News
In their defeat to Necaxa, Pedro de la Vega was replaced by Paul Rothrock in the opening half, though the Sounders say it was for precautionary reasons, while Braudilio Rodrigues was sidelined with a hamstring injury.
Obed Vargas put them in front after just eight minutes on Sunday, his first in the Leagues Cup this season and only his second across all competitions.
Against Guadalajara, the Galaxy were missing Julian Aude because of a knock, while their leading goalscorer in MLS, Dejan Joveljic, was sidelined with a hamstring issue.
Joseph Painstil and Gabriel Pec scored in their previous encounter, with reserve goalkeeper Novak Micovic stopping the final Chivas penalty to give his side an additional point.
Seattle Sounders possible starting lineup:
Thomas; A. Roldan, Andrade, Ragen, Tolo; Paulo, Vargas; C. Roldan, Rusnak, de la Vega; Morris
Los Angeles Galaxy possible starting lineup:
Micovic; Yamane, Neal, Caceres; Cuevas, Brugman, Delgado, Nelson; Pec, Puig; Paintsil
We say: Seattle Sounders 2-2 Los Angeles Galaxy (Seattle Sounders advance on penalties)
The leaky backline of the Galaxy could be their downfall in this encounter, and if it is as close as we anticipate, the Sounders' experience in these big games should serve them well.