All was bright in Aryna Sabalenka's world when she completed a rare 'Sunshine Double' earlier this season.
Becoming only the fifth woman to win the Indian Wells and Miami titles back-to-back, Sabalenka emphasised her position as the dominant player on the WTA Tour and created a 3,000-point lead at the top of the world rankings.
But a difficult period quickly followed - seemingly out of nowhere - leaving the 28-year-old Belarusian clinging on to her position going into the US Open, which starts on Sunday.
Two-time defending champion Sabalenka returns to New York with a 17-7 win-loss record since the Miami triumph, including a chastening French Open quarter-final exit and a disheartening defeat in the Wimbledon fourth round.
It is a record far below the four-time major winner's lofty standards.
With 2,000 points to defend at Flushing Meadows and Kazakhstan's Elena Rybakina now trailing by only 434, Sabalenka must win again to extend her 99-week run as the world number one.
Asked if she felt confident she can rediscover her mojo on the hard courts on which she has thrived, Sabalenka said: "Absolutely. These tough lessons are definitely going to make me way, way stronger and working even harder."
Sabalenka's four Grand Slam singles titles - two Australian Open and two US Open triumphs, all on hard courts - are more than most players can dream of.
However, she has also lost four major finals and six semi-finals, despite a consistency on the biggest stages that is unrivalled among her peers.
The concern in recent months has been Sabalenka's mental focus disappearing in less pressurised situations.
This was most recently apparent in her Cincinnati Open fourth-round defeat by 20-year-old Czech opponent Sara Bejlek. Sabalenka led 5-1 in a first-set tie-break and 4-1 in the second set, but continued to lack composure in the rallies as Bejlek rallied to win 7-6 (9-7) 6-4.
At her previous tournament in Toronto, she lost to Russian world number 19 Ekaterina Alexandrova in the last 16 as her serve crumbled.
During the clay-court swing, Sabalenka capitulated after winning the first set against Hailey Baptiste in Madrid, Sorana Cirstea in Rome and, most notably, Diana Shnaider at Roland Garros.
"I work on my mental side of the game. I've been trying to reset my mind and to come back stronger," a bullish Sabalenka said in New York.
"It's only a matter of time for me to come back."
The drop-off in Sabalenka's results have opened the door for Rybakina, who beat the Belarusian to win the Australian Open in January, to take over as world number one.
Rybakina might not even have to win a match at Flushing Meadows to do that, as she has fewer ranking points to defend than Sabalenka.
However, there are questions over her fitness because of an ankle injury sustained in the Cincinnati quarter-finals.
Rybakina can secure the number one ranking if her nearest rivals - Sabalenka, Jessica Pegula and Coco Gauff - do not win the title.
If Sabalenka does retain the title, Rybakina would still also rise to the top by reaching the semi-finals.
Pegula, 32, has been ultra-consistent for several seasons without landing a major title, but the 2024 finalist hopes her runs to the Washington and Cincinnati finals will provide the platform for another crack at her home Slam.
Gauff, who beat Pegula to the Cincinnati trophy last week, already has the experience of winning in New York after claiming her first major there in 2023.
Twelve months ago, the 22-year-old American's game was clouded by uncertainty but returns with more confidence and fluidity in her serve.
Beneath the leading quartet, the rest of the top 10 also hold either a Grand Slam or WTA 1,000 title - a group led by French Open winner Mirra Andreeva, Wimbledon champion Linda Noskova and six-time major winner Iga Swiatek.
"You can just see how the depth is pretty crazy," said Pegula.
The Serb great, a 24-time Grand Slam champion, insists he has not put an "expiry date" on his extraordinary career. He continues to put himself in the mix for titles as he looks to finally land a standalone record 25th victory which would move him clear of Australia's Margaret Court on the all-time list.
He has reached at least the semi-finals in six of the past seven Slams, but has not gone all the way since triumphing at the 2023 US Open.
Germany's Alexander Zverev leads the seedings as he looks to reach a third straight major final, having won his first Slam at the French Open before losing to Sinner at Wimbledon.
Canadian Open champion Ben Shelton and Cincinnati finalist Frances Tiafoe lead a strong American challenge, while 2024 finalist Taylor Fritz is another hope capable of ending a 23-year wait for a home men's champion.
