'This time I don't want to feel like a year ago.
Osaka is through to a grand slam quarter-final for the first time, after battling past fellow in-form 20-year-old Aryna Sabalenka in a fascinating encounter on Louis Armstrong Stadium.
Her last major title was in Paris in 2014 and it has been 12 years since she won her second Grand Slam title at the US Open as a 19-year-old in 2006.
She started to outrally Sharapova from the baseline while the Russian, who had an outstanding service performance against Ostapenko, struggled to find the usual consistency.
The defeat was also Sharapova's first in 23 matches played under the Flushing Meadows lights - 22 of those on the showpiece Arthur Ashe Stadium.
Maria Sharapova, of Russian Federation, wears a vest over her shoulders as she sits during a changeover in her match against Carla Suarez Navarro, of Spain, during the fourth round of the U.S. Open tennis tournament, Monday, Sept. 3, 2018, in NY.
"I know that she never lost on night session because last night I saw her match a little bit, and they put it on the TV". For me it's totally different, so I'm really happy because I really played a really good match.
"It was a really good present for me", said the Spaniard. I'm grateful that I got the opportunity to play her [and beat her] in Miami [earlier this year].
She will face 2017 runner-up Madison Keys for a place in the semi-finals. "She has a great serve and plenty of experience on this court".
"If I didn't have the belief to keep doing this and to keep having the motivation and the grind of doing this every day in order to get myself in these positions, I don't think I would be here", said Sharapova.
American 14th seed Keys, who was defeated by compatriot Sloane Stephens in the 2017 championship match, fired 25 winners to Cibulkova's seven.
Her bitterest rival Serena Williams, after four rounds, has just nine double faults and has been broken only three times.
She made the fourth round in NY past year, third round in Australia in January, quarter-finals in Paris before a first round exit at Wimbledon.
"I feel like I learned a lot the match I played here two years ago".
Tsurenko was a set and 0-2 down when she said she felt so dizzy that she needed to see a doctor before going on to claim a three-set win. Suarez Navarro was clean off the ground and committed just 20 unforced errors throughout the match.
I feel the cardboard's had an awesome recreation.
Keys was a comfortable victor over Dominika Cibulkova on Monday, triumphing 6-1 6-3 to record a fifth victory in as many meetings with the Slovakian.
Kei Nishikori will be hoping to make another deep run at his most successful Grand Slam event after he easily outclassed Philipp Kohlschreiber 6-3, 6-2, 7-5 to reach the quarter-finals.