Sainsbury's has played down the resignation of Richard Jones, its director of non-food, who has been poached by Tesco.
It is believed Jones was to have played a key role in building Sainsbury's online non-food site, which is due to launch next year as a rival to Tesco Direct.
A Sainsbury's spokeswoman said: "Our strategy for non-food is in place and we are well down the track in rolling out those plans. We have a great non-food senior team in place, with key hires from major competitors in recent months."
But City analyst Blue Oar said: "For Sainsbury's this could not come at a worse time. Non-food is a significant part of the new sales targets."
Jones was behind the launch of the TU clothing brand, which is now worth £300m a year in sales.
He will have a "sourcing and range development role" at Tesco but, as he is tied into a 12-month contract with Sainsbury's, Jones is set for extended gardening leave.