J Sainsbury, Britain's third-biggest supermarket, is set to come under pressure over its sales growth when it updates the market next week, amid signs of a resurgence from rival Tesco, writes Andrea Felsted .

Tesco, whose sales growth has lagged behind that of rivals this year, has said it is catching up and even overtaking its main competitors, in terms of total sales and those from stores open at least a year. Tesco has also said that it was gaining market share.