Star striker Alex Morgan sent the Wave to the semifinals with a goal in extra time. (Orlando Ramirez/USA TODAY Sports)

San Diego needed a goal.

And who better to call on than Golden Boot winner and seasoned goal-scorer Alex Morgan?

It didn’t matter that until a few hours before kick off Morgan was listed as questionable.

It didn’t matter that a knee injury had kept her out of the U.S. women’s national team’s friendly matches with England and Spain at the beginning of October.

The Wave needed their veteran star. And she delivered.

With four minutes gone in the second period of extra time in San Diego’s playoff matchup with the Chicago Red Stars, the Wave set up for a corner kick.

The kick sailed to the far side of the box, and the Red Stars were able to partially clear it. But before they could gain control, or send the ball up the field, Wave forward Sofia Jakobsson corralled the ball and found Morgan.

Morgan, on the edge of the box with a sliver of an angle, managed to fire a shot that sailed past multiple defenders and into the opposite corner of the net.

Red Stars keeper Alyssa Naeher laid on the field, head in hands, as the Wave started celebrating their 2-1 victory in front of an NWSL playoff record crowd.

In the middle of the celebration was Morgan, who battled a knee injury to take the field for the Wave.

“I just wanted to take it day by day,” she told reporters after the match. “I didn’t wanna set any unrealistic expectations for myself, which is why we didn’t really know until pretty much yesterday that I was gonna be playing, and let alone starting, and able to possibly go 90, or 120 minutes. So that was kind of the mindset a couple weeks ago when my injury was seen as something that I can possibly get back in a quick and timely manner.”

Morgan, a longtime member of the USWNT, wasn’t selected for the squad’s friendly matches with England and Spain due to the knee injury, but coach Vlatko Andonovski said if the team was competing in a World Cup, she would have played.

Sunday’s match wasn’t a World Cup game, but it was a chance for the Wave to advance to the NWSL semifinals in their first season of existence.

“That’s why, to me, Alex is MVP, because in big moments she turns up,” Wave coach Casey Stoney said. “I’m massively proud.”

San Diego already stood as the first expansion team to make the NWSL playoffs. The Wave will continue to venture into uncharted territory in the semifinals, where they will take on the Portland Thorns at 5 p.m. ET Sunday.