Top performing hospital trusts will have to work harder if they want to make the grade under the new rating system due to be introduced in October.
Professor Sir Ian Kennedy, chairman of the Healthcare Commission, admitted threestar trusts would not "automatically be graded as excellent".
The Black Country-born health official spoke out during a visit to the West Midlands Rehabilitation Centre, in Selly Oak, Birmingham which he praised as "a great example of what can be achieved for patients."
Since 2002 the number of healthcare organisations across the Midlands awarded two or three stars has almost doubled, but as the NHS cash crisis tightens its grip, Sir Ian admitted the new system would be more rigorous.
"The Healthcare Commission's brief is to assess the performance of all organisations which provide health-care," he said.
"The old system was really 'black and white', so if a trust hit the target that was ticked off, but because we're looking at a wider range of criteria it should not be assumed that a three-star trust will automatically be graded as excellent.
"Not every organisation can be the greatest in the land, but we do expect every trust to meet the core standards, then next year we will expect them to be even better, we do not want to see standards slipping."
In the last round of star ratings, awarded last July, the Royal Wolverhampton Hospitals NHS Trust was stripped of a star, making it a one-star trust.
The impact of its three-year financial recovery plan may affect how it is ranked later this year, while top perform-ing hospitals - including University Hospital Birmingham, Heart of England NHS Foundation Trusts, and Birmingham Children's Hospital - may have to work harder to retain their status.
The new system, which will be presented in a Healthcare Commission report in October, will assess trusts' finances, safety, cleanliness, staff and patient satisfaction, along with clinical criteria.
Sir Ian, who was born in Tipton, Sandwell, and is a lifelong Baggies fan, added: "Every NHS trust has submitted their data, which has been the responsibility of their board which means they're taking more direct responsibility for the care of their patients - which is what they should be doing anyway.
"We are keen to establish whether trusts are facing financial difficulties as we will be dividing our assessment into 'financial management' and 'provision of patient care'.
"We have a duty to report to patients and the public if there is a problem that needs to be addressed."