Waitrose is to test a delivery service which will allow drivers to enter a customer's home while they are out, and put their groceries away.
The trial uses smart lock technology to allow customers to set an access code for their door lock which is deleted when the delivery is complete.
The pilot starting later this month will involve 100 homes in south London.
Profit margins on home deliveries are thin, and one analyst said the aim was to boost loyalty and profitability.
Waitrose, which is owned by the John Lewis Partnership, will be the first UK supermarket to try "in-home" deliveries.
Archie Mason, Waitrose head of business development, said there was "an increasing demand" among customers to make shopping "even more convenient to fit around their busy lifestyles".
"The concept of 'in-home delivery' has started to prove popular in other countries so we are keen to establish if there is an appetite for it in the UK," he said.
Waitrose has teamed up with lock maker Yale to launch the trial.
Participating customers will set a temporary access code for their smart lock which will be sent to Waitrose via a secure app.
The code will be forwarded to the driver at the scheduled delivery time and deleted after the delivery has been made.
The driver will wear a body camera and customers will be able to view the video the next working day, if they wish.
Richard Lim, chief executive of consultancy Retail Economics, said his own research showed a "surprisingly high proportion" of people would be happy to allow drivers access to their homes when they were not there.
Online deliveries operated on "wafer thin margins", he added, and it was "increasingly difficult to make a profit".
"Convenience is the key driver [for this scheme] and in turn that's going to drive loyalty, drive increased basket values and it will drive profitability as well," he said.
He also said there could be potential efficiencies for retailers, if wider delivery windows meant drivers could cut down on the distance travelled between deliveries.
In recent years, the arrival of discounters Aldi and Lidl and the increasing popularity of online delivery has ramped up competition in the supermarket sector.
Last month, Waitrose published results for the six months to 28 September which showed like-for-like sales were up 2.6%, but operating profits fell 12% to £96.4m.