The Chilean got Arsenal's comeback started when he reacted quickest to a flick on by Olivier Giroud and headed past Artur Boruc.
Lucas Perez and Giroud then sealed the fightback to earn a late draw.
Five things we learned about Arsenal against Bournemouth
Tue, January 3, 2017Click through the gallery for five things we learned about Arsenal against Bournemouth
Click through the gallery for five things we learned about Arsenal against Bournemouth
But, after the final whistle, Sanchez was far from happy.
When the referee blew up for full time, Sanchez angrily takes off his gloves and throws them to the floor.
He then trudges off the pitch without acknowledging the away supporters behind him.
Then shows further frustration by throwing his arms up towards his team-mates and walking off the pitch.
The result leaves Arsenal eight points behind leaders Chelsea, who can stretch it to 11 with a win over Tottenham tomorrow.
Sanchez is in the middle of contract negotiations and Arsenal's faltering title challenge is unlikely to help the Gunners in talks.