Tesco and Sainsbury's all apples and oranges over Christmas trading figures

Tesco reports a 1.8% rise in like-for-like sales in the five weeks to 5 January and Sainsbury’s a 0.9% increase in the 14 weeks to the same date. Who's the winner? Photograph: Oli Scarff/Getty Images

There's nothing like Christmas trading figures to bring out the seething rivalry between the big grocers. On Thursday morning it erupted, with a Sainsbury's executive questioning Tesco's like-for-like sales figures.

Sainsbury's was undoubtedly feeling the heat, as its briefings led to the chief executive, Justin King, declaring the supermarket chain the "clear winner" of the Christmas trading period, one day before Tesco came out with apparently better sales figures.

The two chains report on different periods, making a straight comparison impossible. But – looking at the Christmas trading statements alone – Tesco enjoyed 1.8% growth in like-for-like sales, excluding petrol, in the six weeks to 5 January, while Sainsbury's saw the same measure of sales tick up by 0.9%, in the 14 weeks to the same date.