Bellerin will be out for four weeks with an ankle problem while Sanchez played for Chile against Uruguay on Tuesday despite concerns over a hamstring injury.
“We didn't know whether or not he would play 24 hours before the Uruguay game. In the end they decided to play him. He text us saying he was in good shape after the game but we have to wait,” Wenger told reporters on Thursday.
“I will see him tomorrow morning and if he can be involved in the squad or not. What I will consider is basically the risk of injury.”
Bellerin's injury will rule him out of key games, including Wednesday's Champions League clash against French champions Paris St Germain and a London derby against West Ham United next month.
Arsenal will also still be without midfielder Santi Cazorla, who last featured in the Champions League win over Ludogorets in October.
Wenger has yet to beat Mourinho in 13 competitive matches since the Portuguese moved to England with Chelsea in 2004 and the pair have been involved in a number of acrimonious incidents.
“I don't think I have to describe our relationship. He will fight for his team and I will fight for mine and that is normal. Of course, I will shake his hand,” Wenger said.
“I will respect the ritual in the Premier League... It's not the controversy that makes the audience, it's the quality of the game.”
Arsenal are fourth in the table with 24 points, six ahead of sixth-placed United after 11 games.
Original source: Arsenal suffer Bellerin blow