Leapai beat the previously unbeaten Denis Boytsov in November to become the WBO’s mandatory challenger.
"I am wary, but I will prepare myself as well as I can and I'm looking forward to a great challenge," said Klitschko.
Klitschko has a 61-3 record – 52 of his victories coming via knockout – while Leapai boasts a record of 30-4-3.
"Everyone talks to me about Wladimir's 61 victories and how great he is, but all I'm thinking about are his three defeats against opponents who can't strike as hard as I can,” said Leapai.
"I'll beat Wladimir and it won't even be my toughest fight."