Tesco plans to deliver shopping to customers' doors in as little as 10 minutes after launching a partnership with start-up Gorillas.
The chain began a pilot on Thursday from its store in Thornton Heath, South London.
Tesco has already expanded into rapid grocery delivery with its own Whoosh service, which promises to deliver shopping in 60 minutes.
Supermarkets are dealing with renewed competition from start-ups including Gorillas and Getir which offer rapid deliveries and big discounts to attract new customers.
Sainsbury's offers 1-hour deliveries through its Chop Chop app while several other chains are listed on apps including Deliveroo and Uber Eats.
Under the deal announced on Thursday, Gorillas will show a range of Tesco products through its app and set-up fulfillment areas to pick and pack shopping in five large stores.
In Thornton Heath, Gorillas will use warehouse space at the back of the store and stock around 2,000 products.
Jason Tarry, Tesco UK & Republic of Ireland chief executive officer, said: "The idea that we can reach our customers in just 10 minutes is really exciting.
"We are committed to being easily the most convenient choice for our customers, enabling them to shop whenever and however they want.
"This pilot with Gorillas will help customers get their products right away, supporting those looking to buy food for tonight or last-minute forgotten items."
Gorillas announced last week that it had secured $1bn (£730m) of funding from backers including takeaway delivery firm Delivery Hero.
Adrian Frenzel, chief operating officer at Gorillas, said: "We're thrilled to be announcing this first-of-its-kind commercial and real estate partnership with Tesco.
"As a fast-paced company at the forefront of the on-demand grocery industry, we are always looking for ways to innovate, and this co-location partnership will bring unprecedented value to our customers in the UK who will now have the possibility to be delivered the best of Tesco within minutes thanks to Gorillas."
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