Shelton was broken in the opening and closing games of the first set, unable to take advantage of a break point at 2-1 down while Sinner was always capable of pulling out an ace at the crucial time, hitting two in that fourth game to hold serve.
Canada's Felix Auger-Aliassime reached the last four of the ATP Finals with a 6-4, 7-6(4) round-robin win over two-times winner Alexander Zverev on Friday and Jannik Sinner extended his indoor hardcourt unbeaten run by beating American Ben Shelton.
The opening Grand Slam of the year begins at Melbourne Park on Sunday.
Carlos Alcaraz began his bid for a first ATP Finals trophy with a win over Alex de Minaur and Alexander Zverev overpowered Ben Shelton in their round-robin openers.
The 20-year-old will need all of his weapons on Friday if he is to stand a chance in his first meeting with Djokovic.
Zheng Qinwen saw off a spirited challenge from Diana Shnaider to secure a hard-fought 7-6(5), 6-3 win in their Pan Pacific Open semi-final on Saturday and set up a title clash against American Sofia Kenin.
Shelton first through to quarters as action heats up at U.S. Open
Novak Djokovic's quest for a record Grand Slam title continued in dramatic circumstances after fifth seed Lorenzo Musetti quit their Australian Open quarter-final match with an injury after taking a two-set lead at Melbourne Park on Wednesday.
Jannik Sinner and Carlos Alcaraz are poised to reignite their rivalry at the ATP Finals, with the year-ending championship that begins on Sunday expected to produce another title showdown between the pair in a season that has belonged to them.
Defending champion Jannik Sinner reached the semi-finals of the ATP Finals with a 6-4, 6-3 win over two-times winner Alexander Zverev on Wednesday, with Ben Shelton eliminated after losing earlier to Felix Auger-Aliassime in the same group.
Twice defending champion Jessica Pegula crashed out of the Canadian Open after losing to Anastasija Sevastova 3-6, 6-4, 6-1 in the third round on Friday, while six-times major winner Iga Swiatek marched on with a dominant 6-2, 6-2 win over Eva Lys.
IMAGES from the Australian Open matches played at Melbourne Park in Melbourne on Thursday.
'I tried to calm myself as I was mad, angry and talking not really good things. I'm really happy not to let those thoughts play against me.'
Alcaraz off to winning start at ATP Finals with win over De Minaur
IMAGES from Day 9 of the US Open, at the USTA Billie Jean King National Tennis Center, Flushing Meadows, New York.
Novak Djokovic's battling victory under the lights of Arthur Ashe Stadium made him the oldest man to reach the last 16 at the US Open.
Second seed Coco Gauff overcame early problems on serve to cruise past China's Wang Xinyu 6-3, 6-2, keeping her composure despite eight double faults in the first set to book a meeting with Ukraine's Dayana Yastremska in the third round.
Jannik Sinner and Carlos Alcaraz are among the world's top players calling for the Davis Cup to return to its traditional home-and-away format and be staged over two years, a proposal backed by ATP chairman Andrea Gaudenzi.
Jannik Sinner began his bid to retain the ATP Finals title with a resounding 7-5, 6-1 win over injury-hit Canadian Felix Auger-Aliassime in their round-robin clash.
Mboko saved a match point against Kazakh ninth seed Rybakina in front of adoring home support
It marks Osaka's first WTA 1000 semi-final since Miami in 2022, as the Japanese former world number one needed just over an hour to secure victory over the 10th seeded Svitolina.
Novak Djokovic reached the Wimbledon quarter-finals for the 16th time but it proved a hard day's work at his Centre Court office.
The Americans found their rhythm to wrap up a final-day victory
IMAGES from Day 1 of the US Open matches played at Flushing Meadows, New York on Sunday.
Defending champion Jannik Sinner swept past Felix Auger-Aliassime 6-0, 6-2 on Thursday to reach the Cincinnati Open semi-finals, the world number one extending his hardcourt winning streak to 25 matches.
Defending champion Jannik Sinner, who has been recovering from illness, received a more favourable route to the US Open final than Carlos Alcaraz while Aryna Sabalenka will be tested in her bid to retain her title after the draw was made on Thursday.
Defending champion Jannik Sinner and Carlos Alcaraz are aiming for a third successive Grand Slam final meeting when they take their high-voltage rivalry to the US Open while Novak Djokovic looks to foil the new generation as he hunts a 25th major.
World number two Carlos Alcaraz beat seventh seed Arthur Fils 6-2, 6-4 on Saturday to advance into his third Barcelona Open final, where the Spaniard will face Denmark's Holger Rune for the title.
Renata Zarazua, the only Mexican player in the US Open main draw, pulled off a stunning upset by beating sixth seed Madison Keys in the first round.
In the evening session, men's third seed Alexander Zverev and women's fourth seed Jessica Pegula were forced off the court mid-match due to rain and the threat of lightning.
Eugenie Bouchard's best year was 2014 when she reached the semi-finals of the French and Australian Opens, and the final of Wimbledon.
Anna Kalinskaya outclassed Britain's Emma Raducanu at the Washington Open on Saturday to advance to the final, where she will face Leylah Fernandez.
Jannik and Carlos are the favourites at Flushing Meadows, but don't write these men off!
Australia booked their place in the Davis Cup semi-finals as doubles pair Matthew Ebden and Jordan Thompson clinched the deciding rubber against the United States on Thursday.
Iga Swiatek was the latest top player to suffer an upset loss in Montreal as the Wimbledon champion
Elena Rybakina powered into her first Cincinnati Open semi-final after stunning defending champion Aryna Sabalenka 6-1, 6-4 on Friday, while five-times Grand Slam champion Carlos Alcaraz recovered from a second-set blip to beat Andrey Rublev.
American lucky loser Reilly Opelka put up an intense battle to stun top seed Daniil Medvedev 7-6(5), 7-6(5) and reach the semi-finals in Den Bosch on Friday.
Carlos Alcaraz, who advanced to the last eight in Cincinnati for the third time, has now won 36 of his last 38 matches.
Seven-times champion Novak Djokovic scored his 100th match win at Wimbledon and led the march of the old guard into the last 16 on Saturday while an ailing Barbora Krejcikova's title defence ended in defeat and tears.
'We heard it was like the Hollywood of mixed doubles.'
