Crystal Dunn tries breaking away from Seattle’s Utsugi Rumi in second half of Washington’s 2-1 victory. (Katherine Frey/The Washington Post)

Overshadowed by the national anthem controversy, the Washington Spirit defeated the Seattle Reign, 2-1, to clinch home-field advantage in the NWSL playoffs and take a step closer to the Supporters’ Shield.

The Spirit (12-3-3) remains four points ahead of the Portland Thorns (10-3-5) with two matches left. Regardless of the first-place chase, Washington will host a semifinal Sept. 30 or Oct. 1 at Maryland SoccerPlex — the first home playoff match in the club’s four seasons.

Wednesday’s match featured two lightning delays, a missed penalty kick, a potentially serious knee injury to Spirit rookie forward Cali Farquharson and a sensational opening goal by Washington’s Crystal Dunn.

The reigning league scoring champion and MVP recorded her first goal in 12 appearances this year. The U.S. Olympian leads the team in assists with five. In the second half, Seattle’s Hayley Kopmeyer spilled Dunn’s shot, allowing Cheyna Williams’s putback for a 2-0 lead. Kim Little converted a penalty kick for the Reign (6-6-6).

Before Dunn scored, Christine Nairn missed wide right with a penalty kick.

Farquharson (16 appearances, eight starts) will undergo an MRI exam to determine the extent of her injury, suffered in the opening moments. The Spirit is already without its top scorer, Estefania Banini, who is sidelined at least two more weeks with a knee injury.

The Spirit and Reign will meet again Sunday in Seattle (10 p.m. ET, NWSL’s YouTube channel).

Washington is unbeaten in five straight matches (4-0-1) and 7-1-2 at home.

Spirit lineup: Kelsey Wys; Caprice Dydasco, Shelina Zadorsky, Alyssa Kleiner, Estelle Johnson; Christine Nairn, Diana Matheson (Joanna Lohman 57th), Line Sigvardsen Jensen; Francisca Ordega, Cali Farquharson (Crystal Dunn 5th), Cheyna Williams (Ali Krieger 83rd).