Supermarket J Sainsbury has lost ground to rivals for the first time since the recession began, according to confidential 'customer switching' data seen by the Times.Market researcher TNS Worldpanel found that over £11m of spending went elsewhere during the 12 weeks to November.The company, which last week reported a better than expected profit of £342m for the 28 weeks to October 3, lost about £2m to Tesco and £4m to Waitrose.German budget chain Aldi also took a £2.5m chunk out of Justin King's empire, suggesting Sainsbury's faces a two-pronged attack. Both upmarket stores like Waitrose, found to have benefitted from an ill-judged advertising campaign by Marks & Spencer, and the discounters are eroding its market share.The company's aggressive expansion plan, financed by June's £432m fundraising, now look a little ambitious.New chairman David Tyler said last week, the money would support the company's £2bn capital expenditure programme in the two years to March 2011."We're on track to grow gross space 15% over this time and we see potential for growth for many years to come, said Tyler.