Reigning champion Simona Halep edged closer to a third consecutive Madrid Open title by beating Belgium's Elise Mertens on Tuesday.
The world No 1 and top seed converted her fifth match point to win her 14th straight match in the Spanish capital with a 6-0 6-3 victory which was never in doubt.
Halep, the winner in Madrid in 2016 and 2017, ended Mertens' impressive 13-match winning streak, which included titles in Morocco and Switzerland.
Kristyna Pliskova of the Czech Republic will now await Halep in the last 16 as the Romanian continues to prepare for the French Open, where she has twice gone the distance only to finish runner-up.
Halep said on the official WTA website: "I knew she's coming with a lot of confidence. I had to start very strong and aggressive, which I did.
"After I played a few games, I felt really good on court. I felt very confident that I can win that match."
Earlier, Petra Kvitova battled to a 6-3 7-6 (10-8) victory over Puerto Rico's Monica Puig to register her seventh consecutive win.
Kvitova's hard-hitting game lends itself more to the faster surfaces but after lifting the title on clay in Prague at the weekend, she has maintained her momentum here.
The world No 10 will meet either Estonia's Anett Kontaveit or Aliaksandra Sasnovich of Belarus.
The Masters 1000 Series continues throughout this week with our coverage of the ATP Madrid Open on Sky Sports Arena. Check listings for starting times.
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