Johannesburg : Ahead of his preparations for the US Open, two-time Wimbledon champion Rafael Nadal has insisted that he wants to improve his up-and-down form this year in the second half of the season and wants to end it on a successful note. The 14-times Grand Slam champion, who is competing at the ATP and WTA Cincinnati Masters this week, said that the last part of the season is important and he wants to finish feeling better than when he started, Sport24 reported. The world number eight insisted that this was an important week for him and wants to perform well. The 29-year-old has been struggling all round the year to make improvements in the rankings as he dropped to the 10th spot after failing to win a tenth Roland Garros title in June. The Spaniard, who arrived in the Midwest after losing a Montreal quarter-final to Japan’s Kei Nishikori, said that he played well there, adding that he was working more than ever to change the dynamic.