The CC is currently carrying out a second round of meetings with invited parties ahead of the deadline for all responses, which is expected to be in early September.
This week's meeting is likely to be the ACS' last chance to meet face-to-face with the CC ahead of the September date, although an autumn date is a possibility if the commission decides to take action.
The association has been critical of the CC's approach to its inquiry to date, and has raised concerns over both its definition of the market and its gathering of evidence on buying prices from supermarkets and suppliers.
As Convenience Store went to press, ACS bosses were preparing for the discussions and were expected to highlight to the CC issues including predatory pricing activity, the anti-competitive impact of supermarket practices in dealing with suppliers and the permitting of acquisitions of large numbers of convenience stores by multiple grocers in spite of dominant market positions.
ACS chief executive James Lowman said: "Our overriding point from the start has been that the grocery market is competitive and sustainable only if there is a place for a strong independent retail sector. In order to ensure the independent sector remains competitive there has to be intervention to ensure they can compete on a level playing field."
Lowman said the ACS would use the hearing to reinforce the evidence it has submitted based on its analysis of supermarket retail prices and wholesale buying prices.
He added: "We will also take on the claims made by supermarkets about how the Competition Commission should define the market. It is wholly wrong to assume that supermarkets compete only with supermarkets. A healthy market for groceries involves competition between retailers of all types and all sizes."