Angelique Kerber says it's tougher to stay No. 1 than to get there.

The 29-year-old German climbed to the top spot in 2016, winning two Grand Slams, but has slipped to No. 19 this season.

"I think it's not so easy to reach the No. 1 spot, of course," she said in an interview with the WTA Elite Trophy at Zhuhai. "You have to win tournaments, beat good players.”

"It's much more tougher because you have a lot more things [off the court]," she said, adding, "Everyone wants to beat you, and they play always good matches.

"A lot more things [for] you to be careful, so I will say to stay there it's much more tougher.

Kerber said the off-court demands were the biggest adjustment, noting, "You have to change completely your day schedule. I think this is the most complicated thing, because you have to really deal with the things you have to do, and you have to also find time for yourself, practice time."

The two-time Grand Slam champion has been one of five No. 1s this season, which she sees as positive.

"I think it's good because it's open," she said. "Everybody can win against everybody."

Kerber has not won a title since reaching the top ranking.