Top-ranked Rafael Nadal extends his unbeaten run on clay to 31 matches . Nadal begins Barcelona bid in style . The Spaniard has won all four of their meetings this year and is now just one win away from equalling Pete Sampras' record for most titles in a calendar year. 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 .
Top-ranked Rafael Nadal extends his unbeaten run on clay to 31 matches . The Spaniard has won all four of their meetings this year and is now just one win away from equalling Pete Sampras' record for most titles in a calendar year. 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 .