Rafael Nadal fights back to beat Ernests Gulbis at Italian Open

World number five Rafael Nadal recovered from a heavy first-set loss to beat Ernests Gulbis and remain on track for a seventh Italian Open title.

The Spaniard, 26, beat Latvian Gulbis 1-6 7-5 6-4 to reach the quarter-finals at Rome's Foro Italico.

There were more comfortable wins for Novak Djokovic, Roger Federer, Serena Williams and Maria Sharapova.

"I survived a tough match today," said Nadal, who will next face compatriot and fourth seed David Ferrer.

"Now I have another chance to try and go farther. Being in the quarter-finals is fantastic. I'm more than pleased with what I've done since I returned."

Nadal missed over seven months with a knee injury before returning in February, since when he has won five titles and reached seven finals.

"I really don't want to talk about my knee," he added. "I'm fine. I fought a lot to be where I am today.

"These matches like today, where you're in trouble all the time but you keep fighting for every ball, this victory means a lot. To have another one like this is very special."

Serena Williams took her winning streak to 21 matches

Top seed Djokovic, going for his third Rome title, has been having his own injury worries over his ankle pain but saw off Ukraine's Alexandr Dolgopolov 6-1 6-4.

"I've been pain-free for a week but I'm still very cautious in my warm-up and recovery," said the Serb. "I don't think it will bother me any more and I don't think about it when I'm on the court."

Second seed Federer thrashed Gilles Simon 6-1 6-2 to set up a meeting with Jerzy Janowicz, after the Pole knocked out ninth seed Richard Gasquet 3-6 7-6 (7-2) 6-4.

World number one Williams thrashed Slovakia's 14th seed Dominika Cibulkova 6-0 6-1 to take her winning streak to 21 matches, but last year's first-round loss at the French Open remains a motivation.

"Nothing is ever perfect," said the American. "I learned that last year when I felt perfect. I am still in the danger zone."

Second seed Sharapova, going for a hat-trick of titles in Rome, eased past American Sloane Stephens 6-2 6-1, while third seed Victoria Azarenka progressed when Ayumi Morita retired.