Richard Brasher, the UK chief executive at Tesco, has stepped down as the market leading retailer struggles to turn around its domestic sales.
Britain's biggest outlet issued its first profit warning in 20 years earlier this year.
Tesco's Group CEO Philip Clark will now take over the running of the domestic operations.
Brasher had only been in charge of the UK operation for a year. The British arm suffered a disappointing Christmas sales period, which led to a profit warning in January. That's despite a £500m price cut campaign.
Brasher will leave in July and steps down from the Board immediately.
Clarke said: “I have decided to assume responsibility as the CEO of our UK business at this very important time.
"This greater focus will allow me to oversee the improvements that are so important for customers. I completely understand why Richard has decided to leave and want to thank him for the great contribution he has made over many years. The depth of management at Tesco and the strong leadership team across the Group allow me to take a more active role in the UK whilst our other businesses continue to grow.
“Richard has been an architect of our successful format strategy; a true innovator with both Clubcard and the dunnhumby partnership; and over the last ten years has led the transformation of our non-food business and the creation of International Sourcing.
“He will leave behind a UK business which has very strong plans for improvement, and over the last two months these plans are beginning to show progress, in line with our expectations.
"I am more determined than ever that these improvements in the UK will result in a better Tesco and an even better shopping trip for customers.”