Villa have struggled so far this season and currently languish 19th in the table, but Benteke has scored 10 league goals and Allardyce is aware the 22-year-old poses a huge threat to the Hammers.
"He's the biggest threat," Allardyce said.
"He's the man who scores the goals for Aston Villa on a regular basis, he's the focal point for their attacks in that he not only scores goals, but he holds the ball up, he's strong.
"He's had a fantastic start in what must have been a very disappointing season so far for Aston Villa.
"It says a lot for what he is as a player when he's producing what he is in a team that's been struggling for results."