Rafael Nadal put fellow Spaniard David Ferrer firmly in his place as he opened his ATP World Tour
Finals challenge with a crushing 6-3 6-2 victory at the O2 Arena in London.
Ferrer had beaten the world number one three days previously in the semi-finals of the Paris Masters but normal service was resumed as Nadal profited from an error-strewn display by his weary-looking opponent.
Nadal joins Stanislas Wawrinka on top of Group A with one win and he now needs one more victory at the season-ending tournament to finish 2013 on top of the ATP rankings.
Ferrer, ranked third in the world, briefly rallied after slipping 5-0 behind in the second set, snatching a couple more games, but he succumbed meekly when he dragged a forehand into
Later on Tuesday defending champion Novak Djokovic, who still has a slim chance of overtaking Nadal in the rankings, begins his Group B matches with a repeat of last year's final against six-times winner Roger Federer.