SAN FRANCISCO — The Golden State Valkyries’ game against the Phoenix Mercury at Chase Center on Monday was looking like an instant classic for the home team.

Down four with 15 seconds left, the Valkyries tied the game on two fadeaway baskets by French rookie Janelle Salaün. Needing just one more stop, Golden State appeared headed toward overtime to decide, what was up to that point, one of the best games of the WNBA season.

But in anticlimactic fashion, the game ended on a controversial foul that sent Phoenix star Alyssa Thomas to the free throw line with a second left. She hit one of two free throws to give the Mercury a 78-77 win.

The foul drew loud boos from the sold-out crowd of 18,064 and prompted Valkyries coach Natalie Nakase to passionately argue the call with crew chief Eric Brewton.

But to no avail.

Nakase later didn’t mince her words about the final play.

“It’s just very unfortunate that it came down to the last free throw,” Nakase said. “I think the fans here, whether it’s our fans, or whether it is Phoenix Mercury fans, they deserve great moments and great shots. To sit there watching someone win a game off of a free throw, I think there’s a disservice somehow.”

Nakase went on to question whether her status as a first-year head coach is a reason for her team not getting calls down the stretch.

“I’m just asking for consistency,” Nakase said. “I’m begging for consistency. And guess what? If it’s because I’m a rookie coach, then I’ll take the loss. If I have to be better with the refs or if there’s a badge of honor that I have to earn, then I’ll do it, you know? So, yeah, I blame myself.”With the score tied at 77 and six seconds remaining, Phoenix took out the ball on the right sideline.

The Mercury set up a screen-dribble handoff action that aimed to get guard Sami Whitcomb open for a shot at the top of the key. As guard Monique Akoa Makani came off a screen from Thomas, Valkyries guard Tiffany Hayes slipped fighting over the pick, creating an opening for the six-time All-Star to get an open look as she rolled to the basket.

Thomas was met at the rim by Cecilia Zandalasini and Temi Fágbénlé and drew enough contact to garner a foul call from Brewton.

Replays showed Zandalasini made minimal contact and Fágbénlé made a play on the ball as it left Thomas’ hands. A shooting foul was called on Zandalasini and the Valkyries (10-11) could not challenge as they had already used theirs earlier in the game.

Nakase was blunt when asked what she saw on the play.

“I saw absolutely no foul,” Nakase said. “The physicality of the game I felt for Phoenix was 10 times more versus our physicality ... but I saw absolutely no foul. It’s unfortunate that it went that way. I believe you have to win off great shots and that’s part of it. I think we deserve that.”

The loss was the Valkyries’ fourth in five games as they fell below .500 before they traveled to play the Seattle Storm (13-9) today at noon. The Valkyries are 5-7 against Western Conference teams.

This is the third meeting between the Valkyries and Storm. The Valkyries won the last matchup 84-57 on June 30. Hayes scored 21 points to help lead Golden State.