Diana Matheson, left, is shown during Wednesday’s practice. She converted on a penalty kick for the Washington Spirit on Saturday night against the Western New York Flash. (Ricky Carioti/THE WASHINGTON POST)

From the overflow crowd to the late equalizer, the Washington Spirit’s home debut in the National Women’s Soccer League was a rousing success Saturday night. But the 1-1 draw with Western New York ended in concern for Flash striker Abby Wambach, the World Cup and Olympic superstar who suffered a possible concussion after being struck in the face by the ball in the late stages.

Renowned as much for her determination and courage as for her scoring feats, Wambach remained in the match and assisted on her team’s goal in the 85th minute. But at the final whistle, Wambach fell to her knees and later required medical attention.

“She’s not doing too well,” Flash Coach Aaran Lines said.

“She got peppered in the face from point-blank distance,” said Spirit goalkeeper Ashlyn Harris, Wambach’s teammate on the U.S. national team. “I could tell she was pretty dazed. I said, ‘Are you all right?’ She was mumbling. That’s not a good sign.

“She is such a tough competitor. She is just relentless and not going to take herself out. After the game, she looked me in the eyes and said she felt out of it.”

Wambach’s injury dampened an otherwise upbeat evening before a capacity crowd of 4,569 at Maryland SoccerPlex in Boyds. Spirit owner Bill Lynch has said he needs to average 3,000 to sustain the business, which follows in the failed footsteps of the Washington Freedom in the Women’s United Soccer Association (2001-03) and Women’s Professional Soccer (2009-10).

“It turned out to be a great night,” Lynch said. “I just think about what there is to do next. There is still a list of a thousand-plus things to do.”

The sideline bleachers were full of bundled-up fans. Blankets and families covered the gentle hill in the east end and a beer garden offered a casual vantage point behind a goal.

Launched with just five months of preparation, the league received a mixed reception in the first weekend, selling out small facilities in Kansas City (6,784) and Boston (2,634) but drawing well under capacity in New Jersey (2,611) and Chicago (1,255).

NWSL’s flagship franchise, the Portland Thorns, will open Sunday against the Seattle Reign. The Thorns, owned by the group that operates the MLS’s Timbers, sold more than 7,000 season tickets.

The Flash (0-1-1) promises to be the league’s other big attraction. Its home opener is next weekend, although hometown star Wambach is unlikely to play.

Wambach also has strong ties to Washington soccer community, having played for both editions of the Freedom. She greeted swarms of young fans during pregame warmups and received a rousing ovation during player introductions.

Wambach, who is three goals behind Mia Hamm for the scoring record in international play, let two golden chances go unfulfilled in the first 30 minutes. She sent a side-volley from inside the six-yard box off the crossbar and watched Harris make a sensational leaping save on her seven-yard header.

Washington (0-0-2) threatened in the 72nd minute, but Adrianna Franch made a diving save on captain Lori Lindsey’s 26-yard bid.

The Flash went ahead when Wambach flicked a long free kick to the far side, where Samantha Kerr headed it in from three yards. Two minutes later, however, Diana Matheson converted a penalty kick after substitute Jasmyne Spencer was upended in the box.

“It surpassed our expectations,” Matheson said of the turnout. “An amazing home crowd and they were with us until the end. Hopefully they come out every week.”