|Venue: Flushing Meadows, New York, Dates: 31 August-13 September|
|Coverage: Live radio and text commentary on every Andy Murray match plus selected others.|
Serena Williams was two games from defeat before recovering to beat Bethanie Mattek-Sands and keep her Grand Slam hopes alive at the US Open.
The world number one came back to win 3-6 7-5 6-0 in round three at Flushing Meadows.
Williams, 33, is aiming to become the first player to win the calendar Grand Slam since 1988.
Men's top seed Novak Djokovic progressed by beating Andreas Seppi in straight sets.
"I'm not trying to live on the edge," said Williams after another tense victory edged her closer to making history.
Williams' fightback against fellow American Mattek-Sands, ranked 100 places lower, means she remains on course to meet older sister Venus in the quarter-finals in New York.
Two-time champion Venus Williams, the oldest player in the draw at 35, upset 18-year-old 12th seed Belinda Bencic in a 6-3 6-4 win.
Screaming Serena eventually finds rhythm
For the fifth time in her last six matches she fell a break behind, and for the 13th time this year she dropped the first set, but once again Williams found a way to win.
With Mattek-Sands, 30, showing the attacking skills that won her the Australian and French Open doubles titles this year, Williams could not find her feet for the first hour.
The 21-time Grand Slam champion was visibly tense, repeatedly screaming "Come on!" and looking pleadingly at her support team as 11 of 12 break points slipped by.
Her edginess was clear for all to see when two double faults saw her broken when serving for the second set, but three rasping returns finally got her over the line.
Williams, 33, had won all nine of her deciding sets at Grand Slams in 2015 and an early break set her on course to making it 10 out of 10.
Mattek-Sands was swept aside in a final set that lasted 25 minutes, and Williams said: "Players come out really strong - I don't think I came out too slow.
"I was finally able to get some rhythm going in the second. I said, 'You know what Serena, just keep going, keep trying.'"
Williams will next face another American, 19-year-old 19th seed Madison Keys, who beat Agnieszka Radwanska 6-3 6-2.
|31-match Grand Slam winning streak back to 2014 Wimbledon|
|24-match US Open winning streak back to 2011 US Open|
|47-match hard-court winning streak in the United States|
|51-2 record this year (only losses to Kvitova and Bencic)|
Sisters on collision course
Swiss teenager Bencic was only six months old when Venus Williams, unseeded and ranked 66th, made a stunning run to the 1997 final before losing to Martina Hingis.
Eighteen years on, the Swiss great was watching from the stands on Arthur Ashe Stadium as part of her teenage compatriot's team.
Bencic is the only player to have beaten Serena Williams on a hard court this year, but if both sisters remain on course it could now be Venus who provides the major obstacle to her sister's hopes of a calendar Grand Slam.
"Of course I have thought about playing her, and I would like us to have that moment so we can see how it is," said Venus, who has only beaten her sibling once in their seven meetings since 2009.
"We both have to get there. I think we both have a great opportunity to do so, but there are no givens."
Djokovic dizzy, Cilic struggles
World number one Djokovic served out against third-round opponent Seppi at the second attempt to win in straight sets.
The Serb, 28, lost his serve at 5-4 in the third set, only to instantly break back against the 25th-seeded Italian.
Seppi earned two more break points in what turned out to be the final game, only for Djokovic to rediscover his first serve at the perfect time to close out a 6-3 7-5 7-5 victory.
Djokovic revealed afterwards that he had been feeling dizzy on court, saying: "At the beginning, first set, I was struggling. I managed to break through and felt better after that."
Defending champion Marin Cilic saved two set points against Kazakhstan's Mikhail Kukushkin before winning 6-7 (5-7) 7-6 (7-1) 6-3 6-7 (3-7) 6-1 in four hours and 11 minutes.
Top-10 ranked players Milos Raonic and David Ferrer were both eliminated, with Ferrer's conqueror Jeremy Chardy remaining on course to face fellow Frenchman Jo-Wilfried Tsonga - who eased past Ukraine's Sergiy Stakhovsky in straight sets - in the quarter-finals.
Laura Robson's US Open campaign came to an end as she went out of the doubles with Belgian Kirsten Flipkens, going down 6-2 6-3 to fifth seeds Caroline Garcia and Katarina Srebotnik.
Next in line for the former British number one, who is rebuilding her career after a long-term wrist injury, is a return to the lower-level challenger tour in Mexico.
"I'm going to take a lot of bottled water and hope for the best," said the 21-year-old.
Jonny Marray's progress at Flushing Meadows ended as the 34-year-old Englishman and New Zealander Marcus Daniell lost 4-6 6-4 7-6 (7-3) against Austria's Philipp Oswald and Canada's Adil Shamasdin.
Fellow Briton Dom Inglot and Srebotnik were beaten 7-6 (7-3) 3-6 10-5 by seventh seeds Raquel Kops-Jones and Raven Klaasen in the mixed doubles.
But there was better news as Jamie Murray, older brother of Andy, reached round three of the men's competition alongside Australian John Peers.
The eighth seeds, who finished as Wimbledon runners-up earlier this year, earned a 6-1 7-5 victory over Colombia's Santiago Giraldo and Australia's Rameez Junaid.
Quotes of the day
"I like having fun. Why not? We're all young, and it's not an easy life travelling always on the tour. Not much free time. Why not make the best out of it?" Novak Djokovic, who was asked for a celebratory post-win dance for the second match in a row.
"I used to always win in the early days." Venus Williams on how the experience of playing her sister has changed over the years.
"I can't feel my body and I don't really know what's going on." Canada's 25th seed Eugenie Bouchard is overwhelmed after winning three straight matches for the first time since January.
"He's going to tell me straightforward what was bad in the match." Marin Cilic gives an insight into the post-match debrief procedure with coach Goran Ivanisevic.
"I was scared. It's the first time I was cramping. I kept playing and kept trying." Russian 13th seed Ekaterina Makarova battled through a badly timed bout of cramp to serve out on match point against 17th seed Elina Svitolina.