The Gunners boss claims the Chilean superstar wants to stay at The Emirates beyond 2018 and haggling over his salary is the only thing holding things up.
Sanchez, 28, is currently on £130,000-a-week but wants more than £300,000.
Wenger announced at the weekend Sanchez will not be sold in the summer and will stay for the final year of his contract.
But now he is fully confident his main man will remain at Arsenal longer.
He said: “I personally think he will sign and stay here. He is happy here. His desire is as well to stay. That is what I deeply believe.
“The disagreements are more purely contractual. Not on the desire. Both parties have the desire to find an agreement, so I think it will happen.”