The first home-movie style ad, which broke this week, features a young girl holding up a bottle of Heinz Tomato Ketchup and a bottle of Aldi's Bramwells Tomato Ketchup.
She declares that she likes both, but price flashes show that the 570g Heinz bottle costs £1.95, while Aldi's 563g bottle is just 69p 65% less and the ad ends with the strap 'Like Brands. Only Cheaper'.
Heinz shrugged off potential impact of the ad."Consumers will not be fooled by imitators they know no other ketchup will do," said a spokesman for Heinz. "One of the secrets of the world's favourite ketchup is our special tomato know-how."
The campaign was not claiming Aldi products were better than the popular brands, said a spokesman for the retailer. "We are saying our products are like the brands, but cost significantly less."
Future ads would feature comparisons between other everyday products, he added.
Aldi grew its market share from 2.9% to 3.1% in the 12 weeks to 23 January, according to Kantar Worldpanel.