Paris St-Germain are reportedly eyeing a swoop for the Chile star but the Gunners do not want to sell.
Spanish gossip outlet Don Balon claim if Sanchez leaves the Emirates, Arsene Wenger will go all out to sign Benzema.
They also report a promise made to Cristiano Ronaldo by Zinedine Zidane could mean the French forward is allowed to leave the Bernabeu.
Arsenal have already signed striker Alexandre Lacazette from Lyon in a £46.5m deal this summer.
Don Balon say Wenger was ready to offer £53m (€60m) this time last year and still wants the France international.
Earlier today the Arsenal manager made it clear he plans on keeping hold of Sanchez though.
The Gunners boss said: “The decision has been made and we will stick to that.
“The decision is not to sell.”
Bayern Munich and Manchester City have also been linked with Sanchez as the transfer saga revolving around the forward rumbles on.
Arsenal kick off the new season when they play Chelsea in the Community Shield on Sunday, August 6.