SINGAPORE: Simona Halep is still coming to terms with her rise to the top of the world rankings at the start of the month but is trying not to let the euphoria of the achievement distract her at the eight-woman WTA Finals which starts on Sunday. Halep became the first Romanian to reach the summit of the women's rankings when she beat French Open champion Jelena Ostapenko in the semi-finals of the China Open in Beijing, a feat she feels is the high point of her career to date. 'The dream came true. Is just the best feeling that I ever had in my tennis career so far,' the 26-year-old told reporters in Singapore on Saturday. 'It's nice. I'm just enjoying the moment. I cannot describe in words what I feel, but it's a good feeling. I'm happy when I'm going to the courts now,' added Halep, who has won 15 WTA tournaments since her breakthrough year in 2013. Halep is planning a major celebration of her ascent to the top of the rankings at the end of the season but the Romanian remains aware that six of the other seven women at the WTA Finals could usurp her as world number one. 'Well, the day that I won the match against Ostapenko, that was the best day, by far, best feeling. But when I went home, I had all the friends, family close to me, and it was -- I had some good dinners with them,' she added. 'We celebrated a little bit. But I haven't done a big party. So I'm waiting to finish here to go to the holiday and then I will have a big party. 'I think for everyone here, the most important thing is to finish the year as number one, but it is not going to be easy. Here everyone is going to play the best tennis, and every match is going to be like a final, as I said many times. 'So I'm not thinking about that. I play better when I'm not thinking about the ranking. I'm just going to give my best, to try to be focused on what I have to play in each match, and we will see at the end who is going to be number one.' After the win over Ostapenko, Halep was beaten in the Beijing final by Frenchwoman Caroline Garcia and the Romanian will have a little bit of revenge in mind when the duo open Red Group round-robin play with a showdown on Monday. 'She played really well in China and she deserved to win that title,' Halep added of Garcia. 'And of course after all the results that she did this year, she deserves to be here. I can say that I'm excited to meet her again. Maybe I can take the revenge.' Ukraine's Elina Svitolina and Denmark's Caroline Wozniacki are the other two players in the Red Group. Spain's Garbine Muguruza, Czech Karolina Pliskova, American Venus Williams and Latvia's Ostapenko are in the White Group.