Williams began her defence of the Billie Jean King Trophy with a crushing win over Angelique Kerber while second seed Victoria Azarenka, her most likely challenger, struggled past Sara Errani.
Williams' 6-3 6-1 victory over German Kerber lasted only an hour and four minutes - substantially quicker than the first set between Azarenka and Errani in the opening round-robin match at the 16,000-seat Sinan Erdem Dome.
The final match of the evening saw 2011 champion Petra Kvitova defeat third seed Agnieszka Radwanska 6-4 6-4.
Kerber is the only player in the red group ever to have beaten Williams, and one of only four different players the American has lost to since Wimbledon last year.
That came in Cincinnati last summer but there was never any danger of a repeat and Williams reeled off the first three games.
Kerber lost all her group matches on her debut at the season-ending tournament 12 months ago and she made a bad start to the second set when, after a long game, she double-faulted twice to hand Williams another break.
The American has won the title on her two most recent appearances, in 2009 and 2012, and she lost just three points on first serve as she wrapped up victory with the minimum of fuss.
Williams has been in Turkey practising since Saturday, and she said: "It's good to get here and feel the conditions. I have played here before, so I think that helped."
The 32-year-old is bidding for her 11th title from 15 tournaments this year having played more matches than in any other year of her career.
There was no sign of fatigue as Williams easily dealt with everything Kerber threw at her, and she added: "I definitely don't feel as fresh as I did but I definitely feel surprisingly good."
Kerber felt there was nothing more she could have done, saying: "Today she was playing unbelievable and I had actually no chance. I think I served very good, but she was returning unbelievable."
Although Azarenka's win in the white group opener was also straight sets - 7-6 (7/4) 6-2 - it could not have been more different.
The first set alone took an hour and 28 minutes, with Errani leading 5-2 and serving for it three times only to lose out on a tie-break.
Azarenka looked rusty and hesitant until she finally got into her stride to win the last four games and the match after two hours and 14 minutes.
The 24-year-old had been on a three-match losing streak dating back to the US Open semi-finals more than a month ago.
Azarenka said: "I was a little rusty at the beginning. I think it's a little bit expected after a break and playing right away against a top player always makes it a little bit difficult. So I had to make that adaptation during the match.
"It was important to take that first set. It was a big turnaround point and to stay in the moment, to really just try to find a way how to win points and how to win games."
Sixth seed Errani was hampered by pain in her right calf that came on in the tie-break and for which she received treatment early in the second set.
The Italian is the only player to have qualified for both singles and doubles in Turkey, while next weekend she has the Fed Cup final against Russia.
Errani admitted she could not guarantee she would play her remaining two round-robin matches, the second of which is on Wednesday against Li Na.
She said: "I hope to recover. We are trying with the physio to do everything that's good to make it better, but you never know. Tomorrow I will try and I will see."
Kvitova has finished a difficult season strongly and she survived a lengthy final game against Radwanska to clinch victory on her third match point with a successful HawkEye challenge.
Although it was an upset on rankings, it was the fifth time in six meetings the Czech has beaten Radwanska and puts her in a great position to qualify for the semi-finals.
Things do not get any easier for Radwanska, who meets Williams on Wednesday night after Azarenka has faced Jelena Jankovic.