"I had done not many goals", she said of her plans upon returning.
Federer, the five-time champion and looking to end his 10-year wait to add to his total in NY, was beaten by Australia's world No. 55 John Millman 3-6, 7-5, 7-6 (9-7), 7-6 (7-3). Cilic defeated Nishikori in the 2014 final when he won his only Slam title.
Karolina Pliskova defeated Ashleigh Barty, 6-4, 6-4, to book a spot in the quarterfinals against Serena Williams.
Now she's aiming for a strong finish to the year. The Mallorcan lost in the Melbourne quarters, won Roland Garros for an 11th time, and fell to Novak Djokovic in the Wimbledon semis this year.
Stephens, a surprise victor a year ago, had looked in fine form at Flushing Meadows as a number of her fellow top seeds were knocked out.
Isner was trying to become the first American man to reach the U.S. Open semifinals since Andy Roddick in 2006.
Sloane Stephens, of the United States, reaches for a shot from Elise Mertens, of Belgium, during the fourth round of the U.S. Open tennis tournament Sunday, Sept. 2, 2018, in NY. Stephens was on the ropes early in the second set with a deficit of 2-0, but started to make a comeback. The spirit of the game was moving fast in Sevastova's direction as she whipped up a 6-2 first set victory.
Gauff's father, Corey, played basketball at Georgia State and her mother, Candi, ran track at Florida State.
Gauff received a wild card this year into the qualifiers for the main draw at Flushing Meadows, but lost 6-4, 6-1 to Heather Watson of England.
There was a wobble for Williams as she dropped her serve in the second set, coughing up one of her five double faults on break point as Pliskova narrowed the gap to 4-1.
That's where the 19th-seeded Latvian is headed after toppling defending US Open champion Sloane Stephens on Tuesday to break through to the last four in her third straight appearance in the quarter-finals.
Sevastova came into the match having broken her opponent's serve a tournament-leading 23 times.
The third seed struggled throughout on what is expected to be the hottest day of the US Open, failing to take her chances as Sevastova coped better with the challenging conditions.
However Sevastova broke to make it 5-3 and then served out for the win.
"I hope I will enjoy it, playing semi-finals".
The policy is a rule on the women's tour but not the men's.
Defending champion Sloane Stephens was dumped out in the quarter finals of the US Open, losing 2-6.
"It was an awesome journey, this three, four years".
It was too much of the match played in the shadows of an afternoon on court which reaked havoc on the two players.