The 27-year-old was substituted after 104 minutes of the match at MetLife Stadium in New Jersey - which Chile went on to win following a penalty shoot-out - in the wake of a heavy tackle by Gabriel Mercado.
After the match on June 27, Sanchez posted photos on his personal Twitter account of a badly swollen left ankle.
The Chile forward followed those on Thursday with updated images of the heavy bruising which has since developed while he recuperates on a break in New York.
Sanchez added on the social media site: " Fourth day of my vacation, locked up in the hotel bored hahaha...
But I'm already much better."
The Gunners forward then made another post, saying: " YOUR BODY CAN ENDURE ALMOST EVERYTHING..
IT IS YOUR MIND THAT YOU HAVE TO CONVINCE"
Arsenal are scheduled to start their pre-season with a tour to the United States for friendly matches in San Jose and Los Angeles at the end of July
Arsene Wenger's squad have further warm-up games against Viking FK in Stavanger, Norway and then meet Manchester City in Sweden before their domestic campaign kicks off against Liverpool at the Emirates Stadium on August 13
Source : PA
Source: PA