The week ahead: Tesco update to settone for Christmas A TRADING update from retail giant Tesco will shine the spotlight on the supermarket sector this week ahead of the all- important Christmas season. Tesco is expected to report sales slipping back into the red in its third quarter, as rivals turn up the heat on the UK's biggest supermarket chain. The grocery giant gave hope of better trading last month when it said like-for-like sales had edged 0.1 per cent higher in its second quarter. However, analysts are forecasting Wednesday's update to show a return to sales declines after figures from Kantar Worldpanel showed Tesco's market share slipping from 31 per cent to 30.5 per cent in the 12 weeks to 28 October. Nick Coulter, retail analyst at Nomura, is pencilling in a 0.9 per cent fall in like-for-like sales, excluding VAT and fuel, in Tesco's third quarter. Thomson owner Tui Travel is expected to post a jump in profits tomorrow as sunseekers fall in love with the package holiday again. City experts predict the group's underlying operating profit will rise 2 per cent to £480 million in the year to the end of September. In its last update, Tui reported a surge in bookings for next year as families look to avoid another miserable British summer. Andrea Ferraz, analyst at Morgan Stanley, said: "After many years of volume drops, the package holiday appears to be back in vogue." Investors will find out on Thursday how badly handbag group Mulberry was wounded in the first half of its year after demand for luxury goods in Asia slowed. The group warned over profits in October, blaming lower-than-expected international sales and a 4 per cent decline in wholesale shipments. That took the shine off a 13 per cent hike in retail sales to £46.5m, including a 10 per cent rise in UK sales.