McEnroe's two main rivals in the world of tennis were Bjorn BORG and Ivan Lendl. BORG was a Swedish tennis player who won 11 Grand Slam singles titles during his career, while Lendl was a Czech-American professional tennis player who won eight Grand Slam singles titles. Both BORG and Lendl were renowned for their powerful groundstrokes and their ability to stay calm under pressure. They were both fierce competitors of McEnroe, and their matches were some of the most memorable in tennis history.