The fifth-seeded Ferrer improved to 7-0 against Seppi, 15-0 in sets, by beating the 32nd-seeded Italian 6-2, 7-6 (2), 6-3 at Roland Garros on Saturday.
Ferrer, who has lost a total of 26 games through three matches, will face No. 19 Kevin Anderson of South Africa for a place in the quarterfinals. Anderson advanced when Ivo Karlovic retired after one set Saturday.
In 2013 at Roland Garros, Ferrer reached his first Grand Slam final before losing to Rafael Nadal.
Seppi is 1-50 in his last 51 matches against opponents ranked in the top 10.