Nadal continued his perfect start to the European clay-court season having won the Monte Carlo Masters last week with a 6-3, 6-3 win over Philipp Kohlschreiber.
The 14-time Grand Slam champion is now just one win away from matching Argentine legend Guillermo Vilas’s record of 49 clay-court titles.
However, Nadal will have to end Nishikori’s hot-streak of 14 consecutive wins in Barcelona as he swept aside French sixth seed Benoit Paire 6-3, 6-2.