( CNN ) -- At times it was almost painful to watch . At one end of the court the world 's No . 1 female tennis star playing well within herself ; at the other her sister , a long way away from regaining that form and status . `` Venus has had a great week , and honestly , if she had n't had to play so many matches , it would have been a much tougher match , '' Serena Williams said after comfortably beating her older sibling on Saturday to reach the final of the Family Circle Cup in Charleston . The 31-year-old was slightly overstating the rigors of the competition in South Carolina , a tournament that heralded the formation of the women 's tour back in 1973 but has this week attracted just two of the world 's top-10 players . Serena is one , and the other -- 10th-ranked Caroline Wozniacki -- crashed out in the quarterfinals on Friday against Swiss No . 63 Stefanie Vogele . Both Williams sisters won two matches on Friday to set up their first meeting since 2009 , but it was defending champion Serena who looked the least affected as she won 6-1 6-2 in just 54 minutes . `` She 'll never admit it , but I do n't think she was 100 % , '' Serena said of her sister , who was diagnosed with a debilitating autoimmune disease before the 2011 U.S. Open -- a grand slam she has won twice , along with her five Wimbledons . `` But you will never get that out of her . And quite frankly , three matches for her is much tougher than three matches for me . It 's definitely not easy -- because I 'm struggling , and I ca n't imagine what she must be feeling . '' Venus , seeded fifth this week and ranked 24th , brushed off suggestions that her health issues had hindered her . `` I felt pretty good actually -- it would have been nicer to have more space between the matches , but it did not work out , '' the 32-year-old American said . `` But I played under the same circumstances as everyone else , at least in the top half of the draw . `` I had a chance to win the match . We both had rackets . But I did n't take advantage of my chances . I was controlling the points , but then I would miss . `` I have to improve my game . I have to get in these situations more often . I 've been off balance for a long time ; I 'm trying to regain my balance . '' Serena extended her career record over Venus to 14-10 , and has now won 70 of her past 74 matches as she seeks to win the tournament -- played on green clay -- for the third time . `` I love playing on this court , '' said Williams , whose only defeat in her past 22 games on clay came in the first round of last year 's French Open . `` I love this tournament . I think it 's a good clay court . `` Sometimes you play on certain clay courts and they 're not good , and they 're funny , and you ca n't really slide , or it 's just weird . But this one is a really good one , particularly the last two years . '' She will next face former world No . 1 Jelena Jankovic , who ended Vogele 's dream run with a hard-fought victory . The Serbian ninth seed , ranked 18th , triumphed 6-4 6-7 ( 6-8 ) 6-2 in two hours eight minutes . Jankovic also reached the semifinals in Miami last week before losing to Maria Sharapova , who Williams beat in the final for her record sixth title at Key Biscayne . Meanwhile , in the men 's Davis Cup teams competition , the titleholding Czech Republic missed the chance to wrap up a semifinal place after losing in Saturday 's doubles against Kazakhstan . Andrey Golubev and Yuriy Schukin beat Jan Hajek and Radek Stepanek 7-6 ( 7-2 ) 6-4 6-3 to reduce the deficit to 2-1 and give the hosts hope ahead of Sunday 's reverse singles in Astana . Argentina took a 2-1 lead at home to France , as David Nalbandian and Horacio Zeballos defeated Julien Benneteau and Michael Llodra 3-6 7-6 ( 7-3 ) 7-5 6-3 in Buenos Aires .
Serena Williams beats older sister Venus to reach Family Circle Cup final . World No . 1 triumphs in less than an hour as she continues title defense . Williams will next play former top-ranked player Jelena Jankovic . Davis Cup champions Czech Republic lose doubles in Kazakhstan .