Samantha Stosur was made to fight hard as she continued her French Open build-up with a 2-6 6-4 6-0 win over American teenager Christina McHale at the Madrid Masters.
The Australian fifth seed struggled with her serve in the first two sets and was broken twice in each, but found her range in the decider to claim victory in just under two hours and progress to the third round.
US Open champion Stosur will face Czech Petra Cetkovska, who progressed with a 6-4 7-5 win over Spanish qualifier Lourdes Dominguez Lino.
Serena Williams beat Elena Vesnina 6-3 6-1 to reach the second round but older sister Venus lost 6-4 6-1 to Angelique Kerber.
The ninth-seeded Williams fired 13 aces and 40 winners against Vesnina, who was struggling with her game on the slippery blue-clay court.
The Russian lost her balance in the sixth game and set up a break point for Williams, who pulled ahead to lead 4-2.
Williams’ ninth ace of the match provided a set point for the ninth-ranked American to take the first set and wrap up the match against the 68th-ranked Russian in just over an hour.
“I’m feeling good but I wasn’t thrilled,” said Williams, who will face Anastasia Pavlyuchenkova of Russia.
“This is my first tournament in Europe so hopefully I will just keep my good form and just keep going,” she added.
Venus Williams’ third tournament since being sidelined by illness is over after being broken six times by the 12th-seeded German.
The seven-time major champion reached the quarter-finals at Miami and Charleston, North Carolina, earlier this season.
Defending champion Petra Kvitova beat Marina Erakovic 6-2 6-3 in her first round match.
In the men’s tournament, Spain’s Nicolas Almagro rallied to beat Santiago Giraldo of Colombia 6-7 (7-5) 6-3 6-3.
Almagro saved four set points before hitting long to lose the first set in a tiebreaker.
The thirteen-ranked Spanish player broke his opponent in the opening game of the second after adjusting his game to the new court surface to win the match in three sets.
“The court isn’t very good, it’s very slippery,” Almagro said of the unorthodox blue clay court that has been criticised by players after it was introduced for the first time in this year’s tournament.
Other winners Monday included Serbia’s Victor Troicki, Mikhail Youzhny of Russia and American Ryan Harrison who beat Sergiy Stakhovsky of Ukraine, 7-6 (7-3) 7-6 (7-5).
Guillermo Garcia-Lopez of Spain ousted 2006 Australian Open finalist Marcos Baghdatis of Cyprus 6-4 3-6 6-4.
Top-ranked Novak Djokovic begins his title defence on Tuesday against Daniel Gimeno-Traver, who beat Victor Hanescu 7-6 (7-3) 4-6 6-3.
World No.1 Djokovic on Monday joined Rafael Nadal in blasting ATP bosses for allowing the change to blue clay without any consultation with players.
“The only disappointing thing from a player standpoint is that it was decided without players agreeing to it,” Djokovic said.