Ferrero improved his record on clay to 14-1 this season and reached the quarterfinals for the third straight week. He won his first title of the year at the Tennis Masters Series event in Monte Carlo two weeks ago and followed with a semifinal showing at Barcelona.
"I felt very comfortable in my last two matches," Ferrero said. "I view it as just one step further. I am not thinking about the final yet."
"Calleri will be difficult," Ferrero said. "He had a great claycourt season, reaching the semifinals last week in Barcelona, the final in Estoril and winning an important title in Acapulco earlier in the year."
Despite being two of the best claycourt players on tour, Ferrero and Calleri will be squaring off for the first time on Friday.
Fourth seed Gaston Gaudio of Argentina rallied past Galo Blanco of Spain, 3-6, 6-4, 6-4, in a match suspended by rain Wednesday after two sets. Gaudio will try to advance to his third semifinal of the year on Friday when he faces Brazil's Flavio Saretta.
"Galo Blanco has been injured for a while, but it's always complicated to play against him," Gaudio said. "I knew it was going to be a close match. Yesterday, it just wasn't my day. I found it difficult to get into the match.
"When I was down 6-3, 4-2, I knew I was in a bad position. Galo played some loose points and I managed to work my way back. I came out there today feeling much better and very focused."
Also, Armenia's Sargis Sargsian topped Argentina's Franco Squillari, 7-5, 3-6, 6-3, and Christophe Rochus of Belgium dispatched Markus Hipfl of Austria, 6-4, 6-0.