Supermarkets are trying various strategies to adapt to the growing popularity of online shopping. Tesco has lauched same-day click & collect, while Morrisons has struck a deal with Amazon to provide fresh food for the e-commerce giant.
Others have teamed up with delivery services to provide collection points for goods ordered from other retailers to generate revenue from excess store space. Sainsbury's has also agreed a £1.4 billion takeover of Argos, which runs a same-day delivery service.
The shift comes amid the rise of top-up shopping versus a large, weekly shop and continued pressure from discounters Aldi and Lidl, which have forced the big four - Sainsbury's, Tesco, Morrisons and Asda - into a price war.
Sainsbury's is thought to have been among the best at coping with those challenges and is expected to report a 2.4% rise in pretax profits on Wednesday, according to Thomson Reuters data. Sales are predicted to rise 0.4% to £23.5 billion.