China's tennis star Li Na vowed to "fight like crazy" at Wimbledon to keep alive her bid to win a second Grand Slam crown.

The 2011 French Open champion is one of only five seeds left in her half of the draw - though those remaining include the only two ranked above her: titleholder Serena Williams and last year's beaten finalist Agnieszka Radwanska.

However, the Chinese sixth seed is in a buoyant mood and insists she will never roll over in the face of a challenge.

The dearth of seeds is "good for me", the 31-year-old said.

"At least I am still in on Monday," she said, when she faces Italian 11th seed Roberta Vinci for a place in the quarterfinals.

"Now we have a lot of young players coming up. Of course, we can see so many young faces, as well.

"This is tennis. You can imagine always to have some players on the draw. That's why this is an amazing sport because you never know who can be in the next round."

Li is in a combative mood going into week two of the tournament. She went out in the second round on her previous two Wimbledon outings, though her best performances were in 2006 and 2010 when she reached the quarterfinals.

"I'm still hanging in there. Fight like crazy, but still at least I will be in the second week of Wimbledon," she said.

"If I didn't play my best tennis, the only thing I can do is fight on the court. I don't really want to go home.

"Sometimes I was thinking I was fighting a lot on the court. So if Carlos (Rodriguez, her coach) says keep fighting, that means I can do it even more.

"If the chair umpire didn't say game, set and match, you always have chance.

"I never give up."

The Wuhan righthander had to rely on that spirit to get through her third-round match on Saturday.

She came through a disjointed encounter with 32nd seed Klara Zakopalova, winning 4-6, 6-0, 8-6 in a two-hour contest after nearly blowing it in the final set. However, despite going a break down for 6-5 in the deciding set, Li recovered her nerve to finish off her Czech opponent.

She thinks Vinci will prove quite a different challenge on Monday. Li has won all three of their previous matches, in 2001, 2006 and 2011.

"A Grand Slam is the perfect thing because you don't have to play every day. Between them you have one day off, so you can prepare for your next match," she said.

"We had so many years and didn't play face to face. For sure a tough match.

"She has pretty good slice on the backhand. Not so many girls are used to doing that, especially on a grass court. So I have to rally and fight."