Rafael Nadal of Spain celebrates after winning point against Roger Federer of Switzerland during their ATP world Tour Finals tennis semifinal match at the O2 Arena on London, Sunday, Nov. 10, 2013. Rafael Nadal of Spain plays a return to Roger Federer of Switzerland during their ATP World Tour Finals single semifinal tennis match at the O2 Arena in London Sunday, Nov. 10, 2013. Roger Federer of Switzerland plays a return to Rafael Nadal of Spain during their ATP World Tour Finals single semifinal tennis match at the O2 Arena in London Sunday, Nov. 10, 2013. LONDON (AP) - Rafael Nadal ended Roger Federer's hopes of finishing a disappointing season on a high note, defeating the six-time champion 7-5, 6-3 on Sunday in the semifinals of the ATP World Tour Finals. It was Nadal's first win over his old rival on an indoor hard court and his 22nd in 32 matches overall. Nadal, who will finish the season ranked No. 1, is bidding to win the elite year-end event for the first time. He will face either Novak Djokovic or Stanislas Wawrinka in Monday's final. Federer, who has been hampered by a back injury this season, has won only one title over the past 14 months. He played aggressively early but faded after losing the first set, making too many mistakes to threaten the Spaniard.