The department store group, which is one of the two anchors in the scheme, is taking action against Grosvenor following a dispute over the centre’s opening date, which the retailer claims was agreed at March 31.
However, a Grosvenor spokeswoman confirmed that the first phase will open on May 29 and that the March 31 date was given to Debenhams in error.
The retailer is seeking damages of£125,000 a week until Liverpool One opens, which could cost Grosvenor about£1 million if it succeeds.
Grosvenor said at its full-year results on Monday that it had been forced to make a£48.8 million provision against Liverpool One because of a drop in capital value. This was despite record results last year, with pre-tax profits rising 3 per cent to£542 million.
It is the second time Grosvenor has had to make a provision against the scheme in two years.