Williams breezed past Romanian qualifier Simona Halep 6-3 6-0 in a little over an hour for her 23rd consecutive win on the WTA Tour - a run that has seen her win titles in Miami, Charleston and Madrid in recent weeks.
The world number one will be a firm favourite against Azarenka, who was a 6-0 7-5 winner against Italian seventh seed Sara Errani.
Williams has won 11 of her 13 matches against the third-seeded Azarenka and has only lost one of her past 33 matches on clay, her only defeat coming against Virginie Razzano at the French Open last year.
"I don't know if I feel better on clay this year or last year," Williams told the WTA Tour website. "I felt great last year and I feel great this year too. I love clay and have done well on it, even at Roland Garros."
The American is the heavy favourite to triumph in Paris when the French Open gets under way in a little over a week's time but victory over Azarenka would send a statement to her rivals.
Belorussian Azarenka can take a crumb of comfort from the fact she defeated Williams when the pair last met in Doha earlier this year, but she was given a stern test by Errani today.
While the 23-year-old dropped just seven points in the first set, Errani stormed back and nearly took the match to a decider as she served to level proceedings at 5-4 before Azarenka closed out the match.