Serena Williams - Joy following her first round victory
Williams is playing only her second tournament since recovering from a serious foot injury and blood clots on the lungs, which left her in fear of her life.
The 13-time grand slam champion broke down in tears after beating Aravane Rezai 6-3 3-6 6-1 in the first round on Tuesday.
'I think she showed (against Rezai) that once you're a champion, you're always a champion as long as you're always willing to believe in yourself,' said Venus.
'I think she a good role model for anyone. It means a lot to her to be back. I don't think anybody else will ever understand what she's been through.
'As a family we always stayed positive. When times get tough, we always laugh. She stayed positive and I think a lot of people could have got negative.'
Venus Williams has also been sidelined for most of the year, with a hip injury, but she navigated through a 'perfect storm' to beat veteran Kimiko Date-Krumm and reach the third round.
While rain fell outside, Williams and Date-Krumm entertained the Duchess of Cornwall and the Centre Court crowd under the closed roof with some breathtaking tennis.
Date-Krumm took the first set on a tie-break but only after Williams had battled from 5-1 down and saved a total of seven set points.
Williams moved a break up early in the second set to draw level in the match before prevailing in a hard-fought third to clinch a 6-7 (6/8) 6-3 8-6 victory in nearly three hours.
The American had only played four matches since January after suffering the injury at the Australian Open and was relieved to find a way past the 40-year-old.
'I thought she played unbelievable. I thought she had some luck on her side. This is a great surface for her too,' said Williams.
'It was a perfect storm for her to try to get a win. Thankfully I had some answers.'
Vera Zvonareva, last year's beaten finalist, overcame Russian compatriot Elena Vesnina 6-1 7-6 (7/5) and she will meet Tsvetana Pironkova, who beat Petra Martic 6-1 6-4.
Fourth seed Victoria Azarenka cruised into the third round with a 6-0 6-3 victory over Iveta Benesova and will now face Daniela Hantuchova.
British number three Anne Keothavong crashed to a 6-2 6-1 defeat to eighth seed Petra Kvitova, who will now play Roberta Vinci.
Eleventh seed Andrea Petkovic was last on court as darkness fell but teed up a third round meeting with Ksenia Pervak after beating Canadian Stephanie Dubois 6-3 4-6 6-3.
Top seed Caroline Wozniacki and French Open champion Li Na are both in action today while title favourite Maria Sharapova meets British 17-year-old Laura Robson on Court One.
Elena Baltacha, the British number one, tackles 20th seed Shuai Peng from China.