Tesco has sealed a narrow victory, leaving the usually dominant Asda still searching for its first win of the new Grocer 33 year.

Asda won 42 times out of a possible 50 in the year ending 12 June, but since then it has come second for three weeks, losing out to Morrisons two weeks in a row. And now this.

Tesco beat Asda by just 44p this week. Extraordinarily, it did so despite having 10 fewer cheapest products than Asda and no exclusively cheapest products, compared with Asda’s eight. A pack of Fairy dishwasher tablets was the deciding factor. It cost £9 at Asda, but only £6 at Tesco thanks to a half-price promotion.

It is an example of the “logic-defying” promotions in the household category that own-label manufacturer McBride said this week had prompted its announcement of a cost-cutting programme that could result in 400 redundancies.

Morrisons and Sainsbury’s also had the Fairy tablets on deal, even cheaper than Tesco at £5, while Waitrose was selling them for £12. Helped by the Fairy deal, Sainsbury’s came third, but was unable to rival Asda or Tesco because it had the fewest cheapest products of all the supermarkets.

Morrisons came fourth, held back by having the fewest number of products on price-only promotion. There was then a gap of £9.30 between Morrisons and last-placed Waitrose.