And he knows none pose as much threat as striker Toto Tamuz
Last season Ohayon played in his homeland for Ashdod and is well aware of the task which awaits Legia, with Tamuz, who made a late move from Betar Jerusalem this summer, the key concern.
"The whole time I tell my team-mates that we must be very careful (with Tamuz). He has incredible skills," said the 28-year-old, who was given his international debut in 2007 by Hapoel coach Dror Kashtan.
"Last season he was the league top scorer and he was wanted by bigger clubs from outside of Israel.
"He is a deadly threat to Legia."
Ohaynon scored twice against Hapoel in the league last season as Ashdod picked up four points and he believes now they have a weaker squad.
"Hapoel is a good team but not as good as last year. Then they played great, had great players," he told Polish newspaper Super Express.
"After the season the team broke up: goalkeeper Vincent Enyeama went to Lille, Ben Sahar joined Auxerre, Eran Zahavi was sold to Palermo and Gil Vermouth to Kaiserslautern.
"This was the backbone of the team."
Both clubs lost their opening matches, Legia against PSV Eindhoven and Hapoel at home to Rapid Bucharest, and the Tel Aviv side's Croatian midfielder Mirko Oremus admits it is vital they get a win in Poland.
"It is important we return to Israel with three points," he told The Jerusalem Post.
"We were the better team against Rapid but we couldn't convert our chances.
"We need to compensate for that defeat with a win on the road and I think we can do that in Poland."