Seattle Sounders head coach Brian Schmetzer confirmed at training Tuesday that goalkeeper Stefan Frei is in the MLS concussion evaluation protocol following an elbow to the head from the Chicago Fire’s Alan Gordon in the dying seconds of Saturday’s match.

“I had to make sure I said it the right way,” Schmetzer said. “He is in the concussion protocol. That’s what we’re — we’re going to leave it at that. There’s a set (routine), he’s got to do this by a certain day. All those little details. We’ll keep you abreast as the week progresses.”

Gordon’s elbow caught Frei’s left temple as both leapt for a long ball into Seattle’s penalty area in the dying seconds of the 1-1 draw. Frei collapsed to the ground and lay motionless for several seconds as trainers ran out to attend to him, before referee Armando Villarreal blew the whistle for full time before play could restart (this was likely to avoid the formality of a Sounders field player needing to don a keeper uniform, since Seattle had exhausted their three substitutions when it became clear that Frei was unfit to continue).

That Frei is now in the concussion protocol only suggests that he exhibited concussion-like symptoms in post-match observations. The keeper was not made available to media (which is common for players who sustained an injury during the match that required their removal, regardless of severity).

It is impossible to say whether or not Frei will pass the concussion protocols necessary to play in the first Cascadia Cup match of the season against the Portland Timbers Saturday, but it is easy to know that Seattle, which has relied on Frei in big moments throughout the season barring a gaffe at LAFC, would sorely miss one of its marquee players.

Frei is in the midst of another standout season in Seattle. The 32-year-old keeper has 56 saves this season (good for fourth in the league), a 1.29 goals-against average and is one of six keepers across the league to allow 18 goals or fewer while making at least 10 starts.

His primary backup, Bryan Meredith, served as the number three man behind current LAFC keeper Tyler Miller last season. Meredith made 12 appearances for the Sounders back in 2012, compiling a 3-5-3 record with three clean sheets and 14 goals allowed, but has not played a minute in MLS league play since.

In four USL appearances with Sounders 2 this season, Meredith has a 41.2 save percentage and 10 goals allowed. Those numbers are weakened somewhat by the quality of the back lines in front of him, given S2’s developmental role, but it has been clear for several years now that Frei is the unquestioned top dog in Seattle’s goalkeeper hierarchy.

If Frei is unable to go against a Portland team that is unbeaten in its last 11 matches across all competitions (eight wins, three draws), Seattle may find itself under siege in its own penalty area.