Ferrer won two break point chances and battled to a 7-6 (1), 6-2 win and will next face No. 5 seed Kevin Anderson of South Africa.
Anderson downed Sam Querrey of the United States Wednesday 7-6 (2), 6-4. Seventh-seeded Ernests Gulbis of Latvia moved on with a three-set win over qualifier David Goffin.
Britain's Andy Murray, the No. 2 seed, closed out the day's action with a 6-3, 6-4 win over Joao Sousa of Portugal.
UPI horse racing weekend preview
Bo Jackson: I can't help Jameis Winston anymore