NEW YORK -- No.12 seed Coco Gauff opened her US Open campaign with a 6-2, 6-3 win Monday against France's Leolia Jeanjean in the first round. 

Gauff will face either Granby finalist Daria Saville or Romania's Elena Gabriela Ruse next. 

Here are three quick takeaways from the 18-year-old's first career win on Arthur Ashe Stadium:

Gauff's serve was impenetrable: Gauff has been vocal about her desire to transition her game from one built on counter-punching to a more attacking style. Building that pressure on her opponents begins with the serve and when Gauff's motion is clicking, she is tough to beat. It was clicking Monday. 

Gauff fired 8 aces, won 91% of her first-serve points and did not face a single break point in the match. Her first serve topped out at a sizzling 118 mph. 

"I was really nervous, I was feeling the pressure," Gauff said. "It's my first back in the home slam after a final. To be frank, I didn't think I was going to be on Ashe today. Opening the women's draw on Ashe, too, at that.

"But it is nice to break the barrier. I really didn't think about it until after the match was over and then I walked out [to salute] the crowd and said, Wait, I haven't done this before. That's why I told them it was my first win on Ashe."

Gauff recalls the first time she met Serena Williams

Gauff stayed aggressive off the ground: Buoyed by her routine service holds, Gauff controlled the match from the baseline. She finished the 80-minute match with 34 winners to 18 unforced errors while holding Jeanjean to just nine winners. 

Gauff also backed herself when coming forward. The current doubles No.1 came into the net 22 times and won all but five. 

"Today was a good match for me," Gauff said. "I think for the first round usually I'm nervous, but the way I played, I don't think I felt that way."

How Gauff is learning to embrace the expectations

Gauff benefits from Halep's early exit: As Gauff was put through her paces on Ashe Stadium, No.7 seed Simona Halep was struggling against Ukrainian qualifier Daria Snigur on Armstrong. Ranked No.124, Snigur pulled off a massive upset, ousting the Toronto champion in three sets. 

With Halep's loss, Gauff is now the highest-ranked player in her section of the draw, which includes No.20 seed Madison Keys.