Spaniards on the March as Costa and Ferrero Reach Paris Quarters
Costa, who beat an off-form and not fully fit Ferrero 12 months ago in the trophy match, said he was hitting top form after whipping French 32nd seed Arnaud Clement in 6-2, 7-5, 7-5 in 3hr 07min.
In a fourth-round match held over from Sunday, Guillermo Coria, the seventh seed, booked a quarterfinal showdown with second seed Andre Agassi after winning a marathon battle with fellow Argentine Mariano Zabaleta.
Former junior champion Coria led by two sets to one when the tie was halted overnight Sunday because of failing light. He lost the fourth but finally won 6-4, 7-6 (7/4), 5-7, 6-7 (4/7), 6-3 in 4hr 41min, the longest match so far in the tournament.
Costa is still seeking a title since last year's Roland Garros triumph.
The ninth seed had had to struggle through three agonizing five setters to earn the right to face Clement, the final French survivor in the men's draw, AFP reported.
But coming back to the center court arena for the first time since lifting the trophy clearly inspired the 27-year-old and he turned in a hugely improved showing to set up a meeting with either fellow Spaniard Tommy Robredo, the 28th seed, or three-time champion Gustavo Kuerten of Brazil, seeded 15, for a place in the semifinals.
"It was a fantastic match. It was pretty difficult to beat him in front of his home fans. But I played very, very well and I am happy to be through to the quarterfinals.
"This was a very important moment for me. I think I am getting back to last year's level," he insisted.
Costa, who rammed down 11 aces, advanced when Clement hit long. The generally undemonstrative Spaniard punched the air to celebrate a magnificent win after a performance which belied his earlier struggles.
Clement said Costa's best was far too good for him. "I don't think I played a bad match but I lacked a little