British number one Johanna Konta beat 16th seed Magdalena Rybarikova 6-3 7-5 in the first round of the Madrid Open.
Konta, 26, has reached only one quarter-final this season and lost to teenage Hungarian qualifier Fanny Stollar in Charleston last month.
But the world number 23, unseeded in the Spanish capital, beat Slovakia’s Rybarikova in an hour and 59 minutes.
Simona Halep and Caroline Wozniacki – the top two players in the world rankings – secured comfortable wins.
World number one Halep, who has won this event in each of the past two years, needed only 51 minutes to beat Russia’s Ekaterina Makarova 6-1 6-0.
And second seed Wozniacki won nine of the last 10 games to defeat Australia’s world number 24 Daria Gavrilova 6-3 6-1.
Konta joined them in the second round with a third successive victory over Rybarikova.
The Briton, who had won only eight previous matches this season, claimed an early break and moved 5-2 ahead after a 20-minute seventh game in which she staved off four break points.
Having secured the set she had break-point chances in the opening game of the next but it was Rybarikov awho built a 4-1 lead, before Konta won three consecutive games to level at 4-4.
She secured the decisive break in the ninth game and comfortably served out to set up a second-round match with American qualifier Bernarda Pera, the world number 98.
Elsewhere Wimbledon champion Garbine Muguruza, who is aiming to progress beyond the second round of her home tournament for the first time, overcame China’s Peng Shuai 6-4 6-2 in an hour and 39 minutes.
Former world number one Maria Sharapova, who beat Halep to win the Madrid title in 2014, won for the first time since January’s Australian Open as she beat Romania’s Mihaela Buzarnescu 6-4 6-1 in an hour and 22 minutes.
The 31-year-old Russian, who has had an arm injury in recent weeks, had lost her past four matches and dropped out of the top 50 after being beaten in the first round in Stuttgart last week.
But she earned a second-round match with another Romanian – Irina-Camelia Begu.
Begu beat fifth seed Jelena Ostapenko on Saturday, when eighth seed Venus Williams, playing her first match on clay this year, lost the deciding set against 22-year-old Anett Kontaveit of Estonia.