Two of the fiercest rivals within the Magners League, the Blues and Dragons last met at Rodney Parade in April.
A 20-14 win for the Blues that day severely dented the Dragons' chances of an inaugural Play-Off spot while keeping the Blues' own hopes alive until the very end of the final 80 minutes of the regular season.
August's 'friendly' is part of the Martyn Williams Testimonial programme which celebrates the achievements and loyalty of one of the game's most respected players.
Williams has played more than 100 times for the Blues, having switched from Pontypridd to Cardiff four years before the introduction of regional rugby, but the 34-year-old is humbled by the decision to arrange a fixture in his honour.
"I'm not aware of Cardiff or the Blues ever arranging a fixture for a player before so it's very humbling," said Williams.
"When I first joined Cardiff our biggest rivals were always Newport. The atmosphere - because they were local derbies - was always brilliant, so to play another Welsh region in a pre-season friendly is a bit special.
"The Dragons were one of the most improved sides last season and they've got a great squad down there which they've strengthened during the summer. They are starting to get the recognition they maybe should have had earlier.
"We need to build on the wins we had and keep driving forward," added Williams in reference to the Blues' five straight victories at the close of the Magners League season and an historic European triumph in the Amlin Challenge Cup.
"The Dragons match will be quite an intense battle, so it should stand us in good stead."
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