The Gunners striker was forced to miss last Thursday's goalless draw in Colombia after suffering what the Chile Football Association described as a "low-grade muscle injury" during training.
However he was fit enough to take his place in the side and played for 84 minutes, scoring two goals in the process, as they beat Uruguay in CONMEBOL World Cup qualifying on Tuesday.
Sanchez was the star of the show, and Chile coach Juan Antonio Pizzi was quick to pour praise on him.
"Individuals speak for themselves," Pizzi told reporters post-match. "Alexis is among the best players in the world. But I am more in favour of emphasising the strengths of the group. And it is what allowed us to turn the game."
Arsenal boss Arsene Wenger will now be hoping and praying Sanchez does not suffer any reaction and returns to England fit and well ahead of the weekend clash with Manchester United.