SINGAPORE: Garbine Muguruza doubted whether she would ever win again after lifting her first grand slam title in Paris this year.

Second round exits at Wimbledon and the US Open followed the French Open triumph for the Spaniard, who was also knocked out of the singles competition at the Rio Olympics in the third round.

Competing in the eight-woman season-ending WTA Finals in Singapore for the second time, Muguruza told Spanish newspaper Marca: "To win Roland Garros was the best and the worst thing for me this year.

"I felt this incredible adrenaline rush but then you get the blues. Doubts emerge, like 'can I win again?'

"When you are ranked second and the number one spot is almost 1,000 points away, you think the only way is down and that is difficult to manage."

Muguruza, now ranked sixth, says she is learning to cope with the lofty expectations on her, and understanding the need to be patient.

"I have more responsibility, more pressure, more eyes on me and you feel that winning is an obligation. I can be my worst enemy," the 23-year-old told the paper.

She hailed Germany's Angelique Kerber, who ended Serena Williams' status as world number one in September, as a model of consistency.

"Each week she has been there, fighting and getting great results," she said. "Perhaps Williams wins three tournaments and is the best but Kerber each week has reached the semi-finals and has managed to overtake her."