Christmas sales growth at the UK's largest supermarket chain, Tesco, was eclipsed by that reported by its closest rival, Sainsbury, for the first time in years.

The results reported this week confirmed that, while last Christmas Tesco saw a 6.9% increase in like-for-like sales and Sainsbury's a mere 0.4%, this season's trading figures are telling a different story.

Excluding petrol, which saw rapid deflation last year, Tesco's like-for-like sales rose by 6.2% over Christmas and New Year, while Sainsbury recorded a 6.8% rise. Including petrol, Sainsbury's still comes out on top, with 5% like for like growth comparing favourably to Tesco's 4.6%, which was lower than analysts' expectations.

The grocery giant is still outperforming Sainsbury's in terms of volume growth, meanwhile, which excludes the impact of rising or falling prices.

Tesco is continuing to cast doubt on the prospect of its losing share to Sainsbury, however. The group commented: "Our figures to December actually show we are still taking customers from Sainsbury.

"We have been consistent in liking competition and fighting hard. Nothing there will change."

One analyst told the Financial Times that the results were important however: "This is the first real sign that Tesco is not invincible […] The competition is in better shape than it has been for many years - and as Tesco has been so strong for so long it becomes more and more difficult to add growth upon growth upon growth."

Another told the Daily Telegraph: "You would be mad to read too much into the figures but we've all got used to the idea that Tesco always wins. This Christmas, it didn't."