Golden State Valkyries forward Kayla Thornton will be out for the rest of the season with a knee injury, the team announced Friday.

She sustained the injury in practice earlier this week and underwent surgery Friday. The team said the procedure was successful.

It’s a tough loss for Golden State. Thornton is the Valkyries’ leading scorer, averaging 14 points, seven rebounds and 1.5 assists this season. The veteran is in her 10th season in the WNBA and played in her first All-Star Game last weekend, becoming the expansion team’s first All-Star.

With Thornton at the helm, Golden State had been surprising the league. Before her exit, the Valkyries (10-12) were in playoff contention. They have led the league in attendance this season.

Before being drafted by the Valkyries at the expansion draft last December, Thornton won the WNBA title with the New York Liberty and has previously played for the Dallas Wings and the Washington Mystics.