Simona Halep and Caroline Wozniacki both won on a day of few surprises at the Madrid Open.
World number one Halep is holding off a challenge from Wozniacki in Spain, with the Dane sure to climb to the top of the rankings if she out-performs her rival this week.
The duo had little difficulty with their opening matches, though, and were joined in the second round by home favourite Garbine Muguruza.
Sloane Stephens and Petra Kvitova are also through, along with a couple of former world number ones.
RANKINGS TUSSLE UNDER WAY
Both Halep and Wozniacki were triumphant on Sunday as the latter looks to dethrone the former at the rankings summit.
And Wozniacki can certainly be encouraged by her performance, breezing past Daria Gavrilova 6-3 6-1 before reflecting: "I think it's the best clay match that I've had so far this year, so I'm really happy with that."
That form has arrived at a good time to challenge Halep in Madrid, as the two-time defending champion began with a brutal 6-1 6-0 win against Ekaterina Makarova.
"I like to play on this court," said Halep after her 13th straight win in Madrid. "When I come back here, I feel a little bit more relaxed - maybe that's why I can touch my best level every time I play."
MUGURUZA MOVES ON
Spanish star Muguruza acknowledged earlier in the week that she feels more pressure when playing in Madrid, but she did not let it show on Sunday.
The third seed progressed 6-4 6-2 against Peng Shuai, who aided the home favourite with 20 unforced errors.
Although Muguruza has won her first-round match for the fourth time in five years, she is still to make it beyond the second stage and will now look to improve upon that record against Donna Vekic.
"Every year I put a lot of pressure on myself to do well here, so I want to change that, just go out there and use the crowd," she said.
FORMER NUMBER ONES FINDING FORM
Victoria Azarenka's return to the clay, for the first time since the 2016 French Open, was a success as the former world number one reached the second round with a 6-3 6-3 defeat of Aleksandra Krunic.
And another one-time top-ranked player secured a timely victory, with Maria Sharapova winning for the first time on clay this season - the 6-4 6-1 victory against Mihaela Buzarnescu her first since the Australian Open.
Madison Keys, the 13th seed, was among the more notable losers, as she went down in straight sets to Sara Sorribes Tormo.