Spanish tennis player Garbiñe Muguruza on Monday said topping the Women’s Tennis Association rankings made her feel calmer but it weighed heavy on her at the same time.

Despite an early loss to Petra Kvitova of the Czech Republic in the US Open last 16, Muguruza topped the rankings for the first time in her career, following former World No.1 Karolina Pliskova of the Czech Republic’s quarterfinal defeat at Flushing Meadows, reports Efe news agency.

“This is the issue. I slept peacefully when I achieved it, but at the same time I am aware of the burden I am shouldering,” Muguruza said in an interview with EFE in Tokyo, where she was set to compete at the Japan Open, her first tournament as World No. 1.

“On one hand, what an achievement! But there is still a lot of work to do and it will be difficult,” said the first Spanish female player to top the rankings since Arantxa Sanchez in 1995, adding that pressure was part of the game.

The 23-year-old said being World No.1 was “a dream came true. I reached it at a young age, staying there is a lot to play for, and this motivates me to try to improve and to keep what I accomplished.”

Two-time Grand Slam Champion Muguruza what she had achieved was not only thanks to her coach Sam Sumyk, but the whole of her team.

“I would not be here, if it were not for my team _ not just my coach _ but also the people around me during this time, gave me a hand, helped me to learn how to play tennis, to improve mentally, to do a lot of things _ this is a team,” she said.

Muguruza said her goals for this year were to “try to continue playing the same way, get as many victories as possible.”

The Wimbledon champion said that winning titles, playing Grand Slams and traveling motivated her.

With players like Roger Federer of Switzerland, 36, and American sisters Serena and Venus Williams, 36 and 37 respectively, who keep playing at the highest level, Muguruza said she intended to keep playing.

“I see myself playing for a long time. I do not know what the future will bring, but I want to keep playing tennis,” she said.

She said she was giving priority to her career over her social life in order to reach the highest levels: “It is clear that it is either this or that; playing tennis or having a better social life. I think having both at the same time is very difficult.”

She predicted that Serena Williams would return to tennis stronger after giving birth to a baby girl earlier in September.

“I think she will return to competition and she will be as dangerous as she has always been. It is incredible that after being a mother and the best (player in the world), she still has the will and the hunger to return to competition,” she said.