The England forward would have been a free agent at the end of the season, and the club have been in negotiations to close out terms on a lucrative extension which would make Walcott among the highest-paid players at the club with a three-and-half-year contract worth close to £100,000-a-week, boosted by lucrative add-ons.
Wenger will be relieved when the ink is dry on the deal, having helped develop Walcott from a raw talent when bringing him from Southampton seven years ago. "I was scared at some stage, yes, that he could leave because it is like that with the experience I have in negotiations," Wenger said at a press conference.
"When things last too long, it is never a good sign. In that case, it took us some time to get where we want to get. It is still not finalised, but hopefully it will be done by this weekend.
"There is a possibility. My optimism is at 99 per cent now."