Iwata is still chasing his first victory on the Japan Tour although he has been in outstanding form this season with four top tens in five starts including a runner-up finish at the Token Homemate Cup.
45 year old Teshima on the other hand is a veteran of the Japan Golf Tour with six victories to his name although the last of those was nearly eight years ago.
New Zealander, Michael Hendry, leads the Australasians and kept his hopes of a spot at the Open Championship alive although he is seven shots from the lead and in 20th position heading into the weekend.
The leading four players inside the top 12 after 72 holes and not otherwise qualified for the Open Championship earn a start at Royal Liverpool in July.
Other Australasians to make the cut were Richard Tate, Steve Conran, Bred Kennedy, Kurt Barnes and Adam Bland although they are well back.