Venus Williams won the battle of the veterans against Kimiko Date-Krumm on day one at the US Open while Simona Halep was given a scare by an amateur.
At 34, Williams is used to battling players a decade younger than her but she was giving away nearly that amount to Date-Krumm, who turns 44 next month.
And the Japanese player made life very difficult for Williams, dominating the first set of their opening-round clash before the American fought back to triumph 2-6 6-3 6-3.
It was Date-Krumm's debut in Arthur Ashe Stadium, the biggest court in tennis, which was not even built when she reached the quarter-finals at Flushing Meadows in 1993 and '94.
Williams has her own history at the tournament, reaching the final on her debut in 1997 and winning the first of two titles 14 years ago.
She is wearily used to being asked how long she will carry on, and she said: "According to Kimiko, I have another decade.
"She set the prime example. She's top 100 and no one can beat her easily. She's breaking the mould.
"When you're 16, 25 is a few decades away. Now 25 is literally a decade behind me. But I'm going to stay as long as I'm playing well
and as long as there is an opportunity, as long as I want to be here."
Williams has had a difficult few years, not helped by a diagnosis of the auto-immune condition Sjogren's syndrome in 2011.
But this season she has been a force again, winning the lucrative title in Dubai in February and beating sister Serena for the first time in five years to reach the final in Montreal earlier this month.
She also gave eventual champion Petra Kvitova by far her toughest match at Wimbledon this year when they played a classic three-setter in the third round.
Williams does not think any of that is necessarily an indication that she could have a good run here, though, saying: "I have won slams where I didn't feel like I was playing my best.
"I have won when I felt like I wasn't prepared. I felt like I lost when I thought I was playing amazing. You can't ever tell what exactly it's going to take.
"If I would tell you every win that I have had, it took something a little bit different to win that tournament. So unfortunately there is no magic formula besides you better play really well and you better figure it out somehow."
"I have won when I felt like I wasn't prepared. I felt like I lost when I thought I was playing amazing. You can't ever tell what exactly it's going to take" - Venus Williams
Halep is seeded in the top two at a grand slam for the first time but dropped the first set to American college champion Danielle Rose Collins before recovering to win 6-7 (2/7) 6-1 6-2.
Collins does not have a ranking and will be back in class at the University of Virginia on Tuesday.
The 20-year-old said: "It's obviously an incredible experience. It was my childhood dream to play in a grand slam and to play in the US Open. I got that off the bucket list.
"I had a really good experience taking a set off the number two ranked girl in the world. I think there is a lot of positive things to take from it. It can only go up from here for me."
Halep, who reached the French Open final in June, knows expectations of her are very high and struggled at first to handle the occasion on Arthur Ashe.
She said: "It's really difficult the first round of the tournament and today was a big challenge for me because I played the first match of this tournament on centre court.
"It's not easy to manage the situation, but I think after the first set did I very well. I started a little bit nervous, but it's normal. And she played really well. She will have, for sure, a good future."
Fourth seed Agnieszka Radwanska beat Williams to win the title in Montreal and she made an extremely swift start to the tournament with a 6-1 6-0 victory over Sharon Fichman.
The Canadian broke Radwanska's serve in the opening game but was swept aside in just 47 minutes.
Sixth seed Angelique Kerber was given a real scare before defeating Ksenia Pervak 6-2 3-6 7-5 while 18th seed Andrea Petkovic also needed three sets to see off Ons Jabeur.
Garbine Muguruza, who stunned Serena Williams at the French Open, lost her first-round match to Mirjana Lucic-Baroni but there were straight-sets wins for Jelena Jankovic, Sloane Stephens, Alize Cornet and Sabine Lisicki.
Tenth seed Caroline Wozniacki made it through to round two after opponent Magdalena Rybarikova retired in the third set.
The Slovakian was beaten by Petra Kvitova in the final in New Haven on Saturday and called the trainer twice during the opening set here.
She was swiftly 5-0 down but fought back to take the second set before calling it a day when Wozniacki moved 6-1 3-6 2-0 ahead.