LONDON (AFP) - Serena Williams has set her sights on erasing the bitter taste of a disappointing 2014 campaign by re-establishing her supremacy at Wimbledon.

She heads to the All England Club mired in something of a slump following earlier than expected exits from both the Australian and French Opens.

After suffering a shock fourth-round loss to Sabine Lisicki at Wimbledon 12 months ago, she embarked on an extraordinary run that saw her finish 2013 by winning 32 of her 33 matches, a sequence that brought her a 17th Grand Slam title at the US Open.

Since then, she has lost her momentum and although she has won titles in Brisbane, Miami and Rome, she has also suffered losses to the likes of Petra Kvitova, Jana Cepelova, Ana Ivanovic and Alize Cornet.

Her struggles have prompted some to suggest she is finally in decline at age 32.

But those chastening defeats have only strengthened her desire to make amends in London and few would bet against the American adding a sixth Wimbledon singles title to her glittering CV.

She starts her 15th appearance at the grasscourt Grand Slam as the world No.1 and top seed, and should she move one title ahead of her sister and fellow five-time Wimbledon winner Venus, Serena might well label the defeat against Garbine Muguruza at Roland Garros as the turning point.

That second-round exit was a hammer blow to Serena, who lives in Paris for part of the year and works with French coach Patrick Mouratoglou. Before heading home to Miami, she vowed to step up her practice in a bid to avoid a repeat at Wimbledon, which gets under way on Monday.

"I'm going to go home and work five times as hard to make sure I never lose again," she said.

"If I couldn't play better, I would be even more disappointed. But I know I can so I know I have something to look forward to."