Play got underway at 11 a.m. Monday at the U.S. Open on a sunny but hot day for players and fans at the National Tennis Center. NY1’s Pat Kiernan is reporting live from the U.S. Open every mor ning this week and filed the following report on day 1 of the tournament.

As fans filed into the National Tennis Center Monday morning, they saw a lot that was new: an 8,000-seat grandstand court, wider walkways and a new place to relax with artificial turf that looks and feels like grass. And of course, the $100 million retractable stadium roof that was years in the making.

"I haven't been here in seven years, so I can see the transformation," said one fan. "The campus right away, when you walk through, you can see there has been major improvements to the facility, a lot more shade added, which is also a very nice thing to have".

"I play every day, and I want to see how the real game is played," said another fan.

For all of the excitement about the new facilities, the star attraction here is tennis. The big board starts with 128 names on the men's side and 128 names on the women's side. Two weeks from now, the two winners will each leave with $3.5 million.

Tennis center boss Danny Zausner says ultimately, it's about the tennis, but he’s excited to show off his new facilities.

Kiernan: What do you love about this event and what it is for the city?
Zausner: In this particular case, we’ve been planning this for five years. So to be able to see the fans coming out now and that whole "wow" factor is what makes it incredibly special every day.

The forecast says they might need the roof on Thursday. Or maybe, Zausner says, they won’t need it at all this year.

"You never know. The joke is that now that we have a roof, it may not rain for 10 years," he said.

No matter what the weather, it’s going to be a busy week in this part of Queens. The Mets are here all week too.