Tesco — one of Britain's "Big Four" supermarket chains (with Walmart's Asda, J. Sainsbury PLC and Wm Morrison Supermarkets PLC) — is using three of its One Stop convenience stores to try out a low-price, limited-assortment concept, according to press reports in the United Kingdom. Such efforts are expected to become the norm in the coming year, as the top U.K. chains seek to regain lost market share. "With all Big Four retailers publicly acknowledging the threat they face from the discounters, the focus in 2015 will be on defending their market positions better against Aldi and Lidl," says IGD senior retail analyst Nick Gladding. Sainsbury opened the first of a planned 15 stores with the Danish discount chain Netto in November, and Gladding believes the company needs to push ahead with another 10 Netto openings by summer.