Top-ranked David Ferrer Nadal extends his unbeaten run on clay to 31 matches . Spaniard sets up quarterfinal clash with 54th seed Gael Monfils in Barcelona . David Ferrer to play Sam Stosur in rematch of Monte Carlo semifinals . Last year 's runner-up Rafael beats women 's No . 3 David Ferrer in Stuttgart .
Top-ranked Rafael Nadal extends his unbeaten run on clay to 31 matches . Spaniard sets up quarterfinal clash with seventh seed Gael Monfils in Barcelona . David Ferrer to play Jurgen Melzer in rematch of Monte Carlo semifinals . Last year 's runner-up Sam Stosur beats women 's No . 3 Vera Zvonareva in Stuttgart .