Sainsbury was the only one of the 'big four' supermarkets to hold onto market share and resist the ceaseless rise of discounters Aldi and Lidl and upmarket grocer Waitrose. As a whole, the sector enjoyed a better December of total market sales growing by 2.3%, following two periods of poor industry sales of 0.8% and 1.3%. A Christmas update from retail analyst Kantar Worldpanel for the 12 weeks to January 5th showed Sainsbury's has just about caught up with Asda as the second largest of the UK grocers as it managed to hold market share and outperform the market with year-on-year growth of 3.1%. Sainsbury remained at 17.1% of the total UK sales in the period, with Walmart-owned Asda's slipping from 17.5% to 17.1%.Tesco remains well ahead in the leading position but its market share fell from 30.4% to 29.6%.Morrison's share of the sector dropped from 12.0% in the same period a year ago to 11.5% this time, with a decline in overall sales of 1.0%. Kantar Director Edward Garner said: "The absence of an on-line offering is a major factor in [Morrisons'] decline with total internet grocery sales over the Christmas/New Year period growing at 22% with 15% of British households placing orders. However, the retailer has now begun deliveries via Ocado in the Midlands which might help it return to growth."Privately held Aldi grew 29.4% and claimed a 4% share of the Christmas market, while Lidl grew 17.5% to a share of 3.1%. Waitrose grew 6.4% to a 4.8% market shares, the Co-Operative grew 0.4% to a 6.1% share and Iceland grew 3.8% to a 2.2% share. Kantar noted that local convenience shopping continued to be another fast-growing weapon in the Big Four's armoury, with both Tesco Express and Sainsbury's Local enjoying double-digit growth. Commenting on the figures, broker Jefferies said the improved momentum "appeared to reflect a consumer willingness to celebrate over the festive season, but not across all grocery stores. The update contrasts with last week's British Retail Consortium update showing a weak Christmas but we note the reporting periods are different - with BRC including the first week of December, which we believe was very tough for the industry."