The Bees meet Bournemouth later today.
"Semenyo can play wherever he wants to play - he's a fantastic player," said Frank.
"I think he's been the best individual player for Bournemouth this season.
"He is definitely a player we need to look out for and do our best to close down."
He added: "Bournemouth have been fantastic. I think they are one of the most positive teams, when you look at their performances so far this season.
"Andoni and his coaching staff have done a top job. They have a lot of threat going forward: Semenyo, Evanilson, (Justin) Kluivert, (Marcus) Tavernier, and then (Ryan) Christie and (Lewis) Cook. Those six players are very good, very dynamic, they run a lot, they run in behind a lot, they pick up second balls and then they run at you.
"When Bournemouth beat Arsenal and Manchester City, two of the best three teams over the last few years, that deserves a lot of praise.
"But those are the highlights; the rest of us who watch a lot of their games and are aware of all their details.
"I like the way the team is set up, the style of football they play, and they've done something really well down there over the last few seasons.
"But, on the flip side, I think there are things we can do to hurt Bournemouth. I'm convinced we'll come out and perform well."