BY THE GROCER NEWS TEAM Publication of the first of our TradeTrak market share figures, produced by ACNielsen, coincides with the release of Christmas trading statements by many of the retailers included in our table. Our data is for the 12-week period to December 29, so includes the most vital part of the festive trading period. And as all the chains reporting this week define Christmas differently, our figures make it easier to compare how they have fared in terms of market share. The good news for the sector as a whole is that the main retailers have posted healthy like-for-like gains for Christmas, showing they continue to perform strongly. Including petrol, Tesco was ahead 4.6% in the UK on a like-for-like basis in the seven weeks to January 5, while Sainsbury was up 5% on the same measure for the 12 weeks to January 5. In 2001, Sainsbury reported a disastrous Christmas with third quarter like-for-like growth of just 0.7% compared with Tesco's 6.9%. Safeway's like-for-likes, excluding petrol, this year were up 4.1% in the 12 weeks to January 5 ­ compared with 5.9% in 2001. Same store sales in Somerfield outlets were ahead 0.6% in the eight weeks to January 5, while sister chain Kwik Save grew by 3.7%. Much of the debate this week has focused on the rivalry between Tesco and Sainsbury and, in particular, on whether the latter is stealing customers back from its arch rival. That's something Tesco strongly denies. However, our table shows that the real winners over the last 12 weeks of 2001 were Asda and Morrisons which both grew market share by 0.3% year on year. Asda, part of the Wal-Mart empire, does not release figures. But its parent has indicated that Asda's like-for-like growth, excluding petrol, was running in the "low teens" in December ­ described by one analyst as "astounding". As the competition hots up in 2002, our monthly TradeTrak column will help you keep tabs on the real winners and losers. {{ PICK THE CORRECT SECTION }}