Answer
The answer is Rafael Nadal. Nadal holds a remarkable record against his Spanish compatriot Nicolás Almagro, having defeated him in all three of their French Open quarterfinal encounters. Their first meeting came in 2006, where Nadal won in straight sets, setting the tone for their subsequent clashes. In their 2007 and 2008 quarterfinals, Nadal once again proved his dominance, defeating Almagro in four sets on both occasions.