Highly-rated youngster Mana Iwabuchi immediately caught the eye for Japan and a clever one-two left her bearing down on Cecilia Santiago but the goalkeeper manged to keep her out.
From a corner Megumi Takase had a chance but headed against a post. However the opening goal wasn't far away as Iwabuchi led the charge and when the ball rebounded to Takase she scored.
Mexico seemed unruffled by the setback and continued to attack from both flanks. In the 31st minute they equalised following good work from Stephany Mayor. She made ground down the right and her cross was collected by Renae Cuellar who controlled the ball and shot strongly.
Back came Japan with Yuka Kado finding Emi Nakajima but to the rescue for Mexico came Santiago. Three further chances arose for Japan with Iwabuchi at the heart of each one. Two superb passes to Nakajima and Kado failed to result in a goal and she missed out herself when left with another one-one with the keeper.
But with the best opportunities falling to Japan, it was Mexico who went and scored - not once but twice and both before half-time. Charlyn Corral picked up the ball, jinked her way past a couple of defenders and then left Erina Yamane with no chance with her shot. It became 3-1 after Mayor caused more havoc down the right, beating three defenders before crossing onto the head of Nayeli Rangel.
Mexico had lost eight of their previous nine games in the FIFA U-20 Women's World Cup and must have though they were on their way to only their second victory. But Japan rallied strongly after the break and when Iwabuchi took aim from long range Santiago saved well at the expense of a corner. In the 64th minute there was a stroke of luck for the Asian team as, following a corner, the ball struck Cuellar and flew into the net.
Japan went all out for the equaliser and they got their reward with just two minutes remaining when Iwabuchi scored from over 30 metres out to make it 3-3.