The five-time champion, who turned 37 last month, tamed the big-hitting Latvian with a rock-solid performance under the Centre Court roof, winning with something to spare.
Ostapenko turned women's tennis upside down when she rocketed out of the pack to claim her first professional title at the French Open last month and the feisty 20-year-old appeared to be gathering momentum on the All England Club lawns.
A rare French Open/Wimbledon double looked within reach for Ostapenko who had struck 121 winners en route to the last eight.
But old maestro Williams, who had already schooled a 21-year-old and two teenagers en route to her 38th grand slam quarter-final, has seen it all before and barely flinched.
There was a wobble when she dropped serve with a double-fault in the second set -- giving Ostapenko renewed belief -- but she never look ruffled as she reached the semi-finals here for the 10th time in 20 visits.
Making her Centre Court debut Ostapenko was a little more subdued than normal but received a glowing report from the veteran of 75 grand slam campaigns.
"She went for a lot of shots. She competed really well. She kept herself really in the game with her attitude. I thought she just did a lot of things really well and kept it close," Williams, who made her Wimbledon debut in 1997, a few weeks after Ostapenko was born, told reporters.
"I never played her. Didn't really know what to expect. I was really happy to come out on top."
SLOW START
Ostapenko, who three years ago served notice of her talent by winning the Wimbledon junior title, said she paid for the slow start which allowed Williams to sprint into a 3-0 lead.
"I was missing a little bit," Ostapenko, who tasted defeat for the first time in 12 grand slam singles matches, said.
"I was not playing bad, but I was just not playing the way I wanted to play today. I wasn't serving so well."
Ostapenko shoveled a backhand into the net in the second game to gift Williams a break and the American breezed through the opener in 29 minutes -- sealing it when Ostapenko completely missed an attempted service return.
Williams secured an early break in the second set but a double-fault allowed Ostapenko to break back and briefly the Latvian livewire looked dangerous with some bludgeoning winners.
Ostapenko was two points from squaring the match when 10th seed Williams served at 4-5 but narrowly missed the line with a forehand howitzer at 30-30, to the relief of her opponent.
Williams capitalized on some errors to break in the next game and held to love to claim victory.
Since winning Wimbledon in 2008, her seventh major, Williams has only reached the final here once, losing to Serena in 2009.
But without her younger sibling for company this time, however, a sixth title beckons. (Editing by Ed Osmond and Pritha Sarkar)
source: news.abs-cbn.com
