Rafael Nadal reached two singles finals at the ATP Finals.
His first appearance in the championship match came in 2010, when he faced Roger Federer in London. Federer won 6–3, 3–6, 6–1. Nadal returned to the final three years later, in 2013, but Novak Djokovic defeated him 6–3, 6–4. Nadal therefore finished runner-up twice and never won the season-ending singles title.
The ATP Finals are different from a normal knockout tournament because players begin in round-robin groups before the semifinals and final. Nadal made several deep runs without reaching the championship match, including semifinal appearances in 2009, 2011 and 2015. Those semifinal campaigns can make his final total seem higher than it is.
Another source of confusion is Nadal's many finals at other major events, especially the French Open, where he won 14 titles. At the ATP Finals, however, the official singles-final count is only two: 2010 and 2013.