Helenius signed a three-year deal at Villa Park earlier this month, shortly after compatriot Okore had arrived from Nordsjaelland for £4 million.
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"He is very strong - I can't beat him all the time in matches,” Helenius told the club’s official website.
"He is fast and very strong and he is very good with the ball. He just shows he has lots of confidence every time.
"He is a good man for this club and I think he will grab his chance. He is a very good player."
Helenius, who netted 16 times in 33 league games last season, has also played for the Denmark Under-21 side with Okore and he feels that their relationship will be positive for Villa.
He added: "It is fantastic to have another Danish player here.
"I know him and we have played together around 10 times for the U21 team in Denmark.
"We know each other and we know what we are good at and we are not so good at so we can help each other."