"He had a little abdominal strain that he caught on Sunday morning in training and he had a scan two days ago", Wenger told a news conference. "Of course when you have treatment on medical bench it's not easy".
Wenger has revealed how uncertainty over his future last season created a "lack of clarity in the dressing room" and saw players asking him what was going on.
'When you are not completely in or the players feel you are not completely in, it is hard to tell them we go [out to win].
The story says that Sanchez has made it clear that he would only consider an offer of more than £300,000 a week and it still remains to be seen whether he is interested in signing a new deal with the north London side.
Wenger also dismissed media reports linking Alex Oxlade-Chamberlain with rivals, Chelsea. He will not play against Stoke. However, the midfielder is unlikely to be rushed back to action for the game against Leicester as Wenger has enough options in midfield.
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"He is today very conscious of his qualities as well, which he was not always, and I personally believe he will be a very great player".
They defeated Chelsea again when the teams renewed acquaintances at Wembley in last Sunday's Community Shield, winning a penalty shootout 4-1 after a 1-1 draw.
Players like Mesut Ozil, Aaron Ramsey and Per Mertesacker are also uncertain for the Leicester clash.
'I can not say I am immune to criticism - everybody wants to be loved, everybody wants to be loved by the fans.
"I will focus more on the players who had the right number of competitive minutes in recent weeks".
The aforementioned trio were pictured training with the rest of the first-team and are likely to be involved in the match day squad for the first league game of the season.