Despite struggles on serve in the first set, Serena Williams has moved into the fourth round of the Miami Open after beating Zarina Diyas.
Serena Williams made it 750 career wins as she progressed past a spirited Zarina Diyas in the third round to stay on track for a fourth consecutive Miami Open title.
Williams had to grind through a tough match on the way to securing a 7-5 6-3 victory.
Neither player could find their rhythm on serve in an error-strewn first set in which Williams served three double faults to Diyas' two.
Diyas even broke Williams twice, but the world number one bettered that by breaking the 22-year-old three times on the way to claiming the first set.
It looked to be much more straightforward in the second as Williams powered to a 4-0 lead, finding her touch on serve and bullying Dimas on return with her trademark power, but the youngster fought back admirably to 4-3 before the American saw out the match.
Williams hit 27 winners, but also struck 37 unforced errors during the tough contest.
"She started with a new strategy, but I eventually figured it out," Williams said.
"She played well. I saw she's ranked 97 in the world and I thought, 'she's doing great,' she has such a bright future."
Williams will now take on Svetlana Kuznetsova in the fourth round after she saw off Carolina Garcia.