Romania's Simona Halep comfortably defeated Canada's Eugenie Bouchard 6-2, 6-3 on Monday's opening night of the WTA Finals.
In a clash of the only two players making their first appearance at the season-ending championships, Halep lost only four points when getting her first serve into play.
Bouchard was well below her best, racking up 30 unforced errors against 11 from Halep.
Serena Williams won her opening match earlier on Monday, beating Ana Ivanovic 6-4, 6-4 in the other Red Group match, for her 16th consecutive victory at the finals.
Williams came into the finals after injuries forced her out of her previous two outings and following Russian official Shamil Tarpischev's disparaging comments about her and sister Venus.
The top-ranked Williams was shaky in her opening service game, saving two break points, but still took a 4-1 lead. Ivanovic got back on serve but lost the first set when she double-faulted at 15-40 in the final game - one of her seven double-faults.
Ivanovic broke Williams to open the second set but the American immediately broke back and took control, improving her career record against the Serb to 8-1.
Before the WTA Finals, Williams retired from the China Open and Wuhan Open because of illness and a left knee injury that had her in doubt for Singapore. But with the win over Ivanovic, she closed in on Martina Navratilova's record of 21 straight wins at the season-ending tournament.
In Tuesday's White Group matches, Maria Sharapova takes on Caroline Wozniacki and Petra Kvitova faces Agnieszka Radwanska.