Coles chief Steven Cain says the retailer's 48th consecutive quarter of supermarket sales growth despite increased competition from Woolworths is proof a new strategy aimed at winning the trust of customers is gaining traction.

Coles' same-store supermarket sales rose at the slowest pace in 12 years in the September quarter as the retailer struggled to match the gains it enjoyed from handing out free plastic toys and plastic bags a year ago.