 Gregory spent three months as caretaker coach, remaining unbeaten for 11 matches and guiding the Wigan Warriors to the 2003 Super League Grand Final – becoming the first side from outside the top two to make it all the way – before being awarded the job full-time on a 2-year contract.The grand final was lost to the Bradford Bulls.In 2004, it became known that Gregory had been suffering from progressive muscular atrophy, a form of motor neuron disease affecting his nerves and muscles which he had possibly contracted as early as 2001.