There were mixed fortunes for the Williams sisters on the opening day of the Sony Ericsson Championship in Doha.
Second seed Serena was made to work hard for her win, eventually beating number three seed Svetlana Kuznetsova 7-6 (8/6) 7-5 in an even contest.
The American broke four times during a match which lasted almost two hours, while her Russian opponent had three breaks of serve with four double faults proving crucial to the final score.
Defending champ! ion Venus is competing alongside her sister in the Maroon Group, but fell to fifth seed Elena Dementieva 3-6 7-6 (8/6) 6-2 in her opening contest.
It was Dementieva's first win over Venus in five years and the Russian, who had lost the opening set and was trailing 3-1 in the second set before clawing her way back, was thrilled to halt a six-match losing streak against her American opponent.
"I was trying to fight for every point. I was trying to stay positive," Dementieva said. "It was very important to come back and win the tie-break.
"I think she was a little disappointed in the beginning of the third set and gave me a little bit of an advantage, and I was able to finish the match."
Williams had nothing but praise for Dementieva's fighting spirit.
"She really stayed in there. She did really well," Williams said.
"I just didn't put enough balls in the court. It was a tough loss."
In the White Group, Victoria Azarenka made sh! ort work of Jelena Jankovic on her debut in Doha.
The B! elorussi an raced to a 6-2 6-3 win over her Serbian opponent in one hour 22 minutes in the opening match of the tournament, which features the top eight players in the world.
Azarenka broke twice in the first set and three times in the second to pave the way for victory.
"I had a good game plan today and followed it well," Azarenka said.
"I was also rested. I didn't play the last few weeks so I had everything to give here."
Russian Dinara Safina, the world number one, and Denmark's Caroline Wozniacki are also in the White Group.
The top two players from each group advance to the semi-finals.
