The 26-year-old struck the opening goal to spark Arsenal's 5-0 Premier League rout of Huddersfield at the Emirates Stadium on Wednesday, only to trudge out of the clash at half-time.
“Lacazette has a groin problem and will be out certainly for Saturday's game,” said Wenger.
Arsenal laboured for fluency and precision after claiming the early lead, but eventually took full control in the final quarter.
Germany playmaker Mesut Özil dominated the late proceedings, ending the night with two assists and a goal of his own.
Wenger insisted the star creator has added new levels of “fight” to his approach in recent weeks.
“Nobody has to convince us he's a great football player,” said Wenger, of Özil.
“Everybody knows in the stadium he's a great football player, but at the moment as well he shows he can fight.
“Our job is to encourage people to fight, but I think he always covered the distances in games, but he's at an age where he's more mature and understands what is more important and what is less important.
“Everybody wants to be acknowledged for his quality, and the judgements are sometimes harsh in a footballer's job.
“But overall I believe the majority of people here love him, and always loved him.
“When you look at the percentage of possession during a game, no matter what the game is, he always wants the ball. He never hides, he's always available.
“If you are dominated you touch the ball less, but when you win the ball, he always wants the ball.”
David Wagner shook off Huddersfield's hefty defeat without delay, insisting his men can still comfortably beat the Premier League drop this term.
“We are strong enough to leave these two defeats behind us very quickly, because we know what we've done wrong and what we need to solve,” said Wagner.
“I'm very confident we can stay in the division, with everything we've done and what I've seen in the 14 games so far.
“If we are strong enough mentally and can keep our key players healthy.”
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