In the run-up to the first game the Nigerians had been training in Durban - which is not a high-altitude venue - before travelling to Johannesburg on Friday, giving the squad only one day to acclimatise to the conditions.
Irvine also avoided injury by not over-training, building up to the distance he was to run in increments (twenty minutes run then building up to two hours) and stretching after a run.
Non-regular workers receive little training, so that Japanese firms run the risk of ending up with a cohort of unskilled, middle-aged non-regular staff.