NEW YORK -- Coco Gauff knew the perfect word to describe her victory on Day 1 of the US Open on Monday night.
"Slow," Gauff said during her on-court interview, before sort of suppressing a smile, pausing for effect and drawing laughter from a packed Arthur Ashe Stadium crowd that had rattled her opponent, Laura Siegemund.
What Gauff meant was the pace of Siegemund, a 35-year-old qualifier from Germany who took her sweet time between points and never seemed ready to play when the 19-year-old from Florida was. The sixth-seeded Gauff also could have been referring to her own start to the match, one she eventually turned around to prevail 3-6, 6-2, 6-4 and reach the second round at Flushing Meadows.
"I was really patient the whole match. She was going over the time since the first set. I never said anything. I would look at the umpire, and she didn't do anything," said Gauff, who got into a lengthy discussion with official Marijana Veljovic in the third set. "Then obviously the crowd started to notice that she was taking long, so you would hear people in the crowd yelling, 'Time!'"
Siegemund, whose faults drew applause and whose own back-and-forth with Veljovic drew jeers, cried during her postmatch news conference, saying the fans "had no respect for me."
"I am very, very disappointed [by] the way the people treated me today," said Siegemund, who has won US Open titles in women's doubles and mixed doubles. "This is something that I have to say hurts really bad. There is no doubt that I'm slow. ... I should be quicker. But at the same time, it's how I play."
As Siegemund added, "They treated me like I was a bad person."
Siegemund outplayed Gauff for the first set, using all manner of slices and superb volleying.
Gauff had lost her previous two Grand Slam matches -- including a first-round exit at Wimbledon last month -- and she did not want to leave quietly or quickly this time. With thousands of partisan fans getting rowdier by the moment, Gauff converted her eighth break point in a 30-point, 25-plus-minute game to begin the second set.
"It was a great mental boost," Gauff said. "That game was a vital momentum-changer."
It put Gauff in front for good.
In the third set, Veljovic called Siegemund for a time violation. Brad Gilbert, who is one of two coaches working with Gauff lately, shook his head at how long it took Veljovic to intervene, and his reaction drew a smile from Gauff.
Serving while ahead 3-0 in that set, Gauff had enough and went over to make her case.
"She's never ready when I'm serving. ... How is this fair?" Gauff told Veljovic. "I'm going a normal speed. Ask any ref here. ... I've been quiet the whole match. ... Now it's ridiculous. I don't care what she's doing on her serve, but [on] my serve, she has to be ready."
Gauff wound up dropping that game. Later, Siegemund was docked a point for delaying, which put Gauff up 5-1. That prompted Siegemund to argue her case to Veljovic -- "I can't go to the towel anymore?" -- and it drew some boos.
There was another hiccup for Gauff toward the finish: She served for the match at 5-2 in the third but double-faulted three times. Those were her only double faults of the entire 2-hour, 51-minute match.
In the end, she held on, and it was Gauff's 12th victory in 13 matches since the disappointing showing at the All England Club. This recent run includes the two biggest titles of the American's career and a win over No. 1 Iga Swiatek. Gauff and Swiatek could meet in the quarterfinals here next week.
Gauff explained during her postmatch news conference she doesn't "like confrontation all that much" but that she finally reached a point of frustration in which she elected to say something to the chair umpire.
"I wasn't sure if I was in the right or not until it, like, happened multiple times," Gauff said, referring to Siegemund's delay tactics between points. "Then I was like, OK, I know I'm in the right. ... For me, I try my best not to let my emotions take over myself. I wanted to express my frustration but also being censored. ... I was trying to best communicate how I was feeling to the referee."
"[She] said it's good to speak up for myself. I think she was happy that I spoke up for myself today."Coco Gauff, on the advice former first lady Michelle Obama gave her
Former President Barack Obama and his wife, Michelle, were in the Arthur Ashe Stadium stands to watch Gauff's first-round victory. After the match, Michelle Obama went down on the court to participate in a tribute to Billie Jean King marking the 50th anniversary of the US Open becoming the first major sports event to pay equal prize money to women.
"I didn't see them in the presidential box," Gauff said about the Obamas. "I was obviously looking at that, but they weren't, I guess, in my eyeline. But afterward, they told me they wanted to say hi."
Initially, Gauff explained, word came that she would have some time with Michelle Obama.
"Then Mr. Obama was there in the room too. I was like, 'Oh, my God,'" Gauff said with a big smile at her postmatch news conference. "I haven't soaked it in because I literally just walked in here. I think I'm going to never forget that moment for the rest of my life. I went from being really upset after a win to, like, being really happy. So I'm glad I got to meet them. They gave me some good advice too."
And the bit of wisdom that was offered?
The former first lady "said it's good to speak up for myself. I think she was happy that I spoke up for myself today," recounted Gauff, referring to a discussion with the chair umpire about the way Siegemund took extra time between points.
ESPN's D'Arcy Maine and The Associated Press contributed to this report.