The Chile forward's transfer to Old Trafford is expected to be completed soon, with Sanchez posting a video on Instagram on Sunday showing him boarding a private plane ahead of a reported medical.
Sanchez reportedly said goodbye to his Arsenal teammates Friday night, with Henrikh Mkhitaryan (supposedly going the other way, from United to Arsenal) also said to have given his farewells to his mates.
The Mirror said the deals may not be officially completed until Monday as both Sanchez and Mkhitaryan are non-EU players and must have their work permits ratified by their new clubs.
"I can not understand anybody wanting to leave Arsenal", Wenger said.
Alexis Sanchez will most likely presented to the media as a Manchester United player on Tuesday, according to Guillem Balague.
Wenger also admitted the uncertainty over Sanchez's future has taken its toll on the rest of the squad this season.
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The money states received from the legal settlements was used to offset medical costs and fund anti-smoking campaigns. Chicago was among the first to do so in 2014 ; the lawsuit is yet to be resolved.
Speaking after Manchester United beat Burnley 1-0 yesterday, Jose Mourinho provided an update. With Sanchez in the team, United now suddenly boast one of the strongest attacks in Europe and will pose a big threat to other big teams.
"In these kind of things, as long as it's not over the line you can not say it will happen because the negotiations become more and more longer and edgy because every detail becomes important nowadays".
"I'm very excited to get a player in who will be committed and focused".
He is acutely aware of the kind of figures that now appear to be considered acceptable by United in terms of wages for their best players.
Armenia worldwide winger Mkhitaryan, also 29, fell out of favour with United manager Mourinho after just 18 months at Old Trafford.
Arsenal have been heavily linked with Pierre-Emerick Aubameyang, with Borussia Dortmund claiming the Gunners made a bid for over the weekend.