Angelique Kerber has suffered an alarming drop in form this year following her stellar 2016, and her fellow German Martin Kaymer has advised her to ignore external criticism.

Kerber enjoyed a stunning season last year, lifting both the Australian and US Open titles as well as finishing runner-up at the Olympics, the WTA Tour finals and Wimbledon, where she was beaten by Serena Williams.

Her displays across 2016 saw her overtake Williams at the top of the WTA rankings, where she remains, but this year has been a story of starkly contrasting fortunes.

Kerber suffered fourth and first-round grand slam exits in Melbourne and Paris respectively, while she also saw campaigns in Stuttgart, Madrid and Rome end early before opting to withdraw from this week's Aegon Classic to rest a hamstring injury ahead of Wimbledon, which gets under way on July 3.

Kaymer is no stranger to the peaks and troughs of elite professional sport, having steadily tumbled down the world golf rankings after ascending to the summit in 2011.

"How she is going to make her way back is very tough because there are many influences you do not expect," the two-time major champion and world number 56 said in a news conference ahead of this week's BMW International Open.

"People tell you things you do not want to hear. And I learned to not take other opinions too seriously because other people do not really know what they are talking about.

"They are not part of this inner circle and they do not know the personality and the character behind [you].

"And therefore the opinion you get through social media or other media you can just take parts of it seriously because these people do not know how the reality is.

"I think it is important to distance yourself from this and you should not let it get close to you.

"The basic thing is, and I think everyone understands this, that you should not the take number one position too seriously.

"Because in the end it is about sports and we are playing a game. We can cause a change or we inspire people which is very beautiful and not many can make people being excited to do certain things."