LONDON • Serena Williams has called on fans to support her sister Venus when the two five-time Wimbledon champions meet in a fourth-round clash tomorrow.

The sisters, who have 27 Grand Slam titles between them, will be on opposing sides of the net for the sixth time at Wimbledon and the 26th time in their careers.

Venus, 35, thrashed Aleksandra Krunic to reach the last 16 while Serena, 33, had to survive an almighty scare against Britain's Heather Watson before guaranteeing the first all-Williams tie at Wimbledon since 2009.

Since Serena won that final clash six years ago, the sisters' paths have diverged, with the younger sibling putting herself among the all-time greats by reaching 20 Grand Slam titles.

In contrast, Venus has slumped down the rankings as she fights a constant battle with auto-immune disease Sjogren's syndrome that often leaves her exhausted.

As a result, Serena believes Venus' struggles deserve the sympathy of the All England Club crowd if they have to pick sides.

"I expect more people to be rooting for Venus," said Serena.

"I would be rooting for Venus. She's been through so much.

"She's had a wonderful story.

"She's been so inspiring to a lot of people with the same things that she goes through."

Venus returned the compliment, saying she would support Serena if she were a neutral fan.

Regardless of the result, Serena said seven-time Major winner Venus had already left a great legacy as a "pioneer" for both the sport - and women's rights.

"She has done so much for this sport," she observed.

"It's just been amazing for me to follow in her footsteps in terms of getting equal prize money here, just stepping up to the plate and being that person."

AGENCE FRANCE-PRESSE