With a trading statement from Tesco expected tomorrow, JP Morgan has taken the opportunity to restate worries about the performance of the company's core UK grocery business.The retailer is expected to show an improvement in like for like (LFL) sales but nothing like the sort of growth rates seen from rivals such as Sainsbuy, due to report on Wednesday, and Wm. Morrison, which updated the market in the first week of June. With Tesco's rivals catching up on the UK's number one retailer JP Morgan has reiterated its 'underweight' rating and 300p price target, though it likes the increasing emphasis the company is putting on personal finance.'We estimate TPF [Tesco Personal Finance] could add 5p per annum to Tesco's share value over the next six years,' the US investment bank said.