Rafael Nadal wanted to play his last match before retiring in Spain, representing Spain and wearing the red uniform used by Spain’s Davis Cup squad. “The feeling to play for your country, the feeling to play for your teammates … when you win, everybody wins; when you lose, everybody loses, no?” Nadal, a 22-time Grand Slam champion, said a day before his career ended when his nation was eliminated by the Netherlands at the annual competition. The men’s Davis Cup, which concludes Sunday in this seaside city in southern Spain, and the women’s Billie Jean King Cup, which wrapped up Wednesday with Italy as its champion, give tennis players a rare taste of what professional athletes in soccer, football, basketball, baseball, hockey and more are so used to.