Coric played a hyper-clean match, hitting 20 aces and producing 20 winners and only three unforced errors. He also saved all five break points he faced.
"It's amazing feeling," Coric said. "I came here and I was only thinking about getting in the main draw. That was my first goal. I said to myself, 'If I achieve that that's going to be perfect.'
"Now actually winning [over] a guy who is top 30 or close, it's just unbelievable. Now my schedule is going to change. All the things are going to be a little bit easier now."
Coric, ranked No. 204 in the world, said he enjoyed watching Kyrgios' swift ascent at Wimbledon, but added, "It showed that even younger players can play with the top 10 or maybe top 20 level. It actually showed me that we can all play with them.
"But also, I'm just looking at myself."
Coric's first big taste of ATP play came in Umag, Croatia, where he got to the quarterfinals back in July. He says he's gotten advice from all the Croatian legends, including Goran Ivanisevic, Ivan Ljubicic and Marin Cilic.
"I think we are coming through," Coric said. "There is four guys or maybe five my age, and some of them a little bit even younger. But, I mean, we need to stay out of the injuries or how to go crazy in the head, so we see who's going to make it to the top 10 or even better."
The Wimbledon junior boys' champion, playing in his first Grand Slam main draw, was overwhelmed.
"Definitely things to learn," Rubin said. "Fitness is one. I mean, nerves came into play a little bit also. Gas was definitely an issue. It didn't help that nerves were there, also. So there were definitely points throughout the whole match I could have capitalized on and I didn't."
Rubin is heading off to Wake Forest, where he'll be a freshman taking art history, writing, astronomy and introduction to Judaism.
Petra nearly perfect
Outside of Serena Williams, no one came in here playing better than No. 3 seed Petra Kvitova. The Wimbledon and New Haven champion had a routine first-round experience, defeating Kristina Mladenovic 6-1, 6-0 -- in 54 minutes.
And to think Kvitova woke up Tuesday morning feeling nervous. Maybe it was because the last time she won Wimbledon (three years ago), she lost in the first round of the US Open.
"I'm just glad that I'm better already," Kvitova said afterward. "The other Grand Slams are a big challenge for me right now to do a good result. Especially here, where I don't really have a good result. So I'm really motivated to do well here."
Kvitova, who won 56 of 81 points, has never advanced past the fourth round in New York; she's been to at least the semifinals in each of the other three majors.
No. 4 seed David Ferrer struggled briefly before beating Damir Dzumhur 6-1, 6-2, 2-6, 6-2. Ferrer, at 32, is a decade older than Dzumhur, the No. 1 player from Bosnia-Herzegovina, ranked at No. 119. ... No. 10 Kei Nishikori handled American Wayne Odesnik 6-2, 6-4, 6-2. ... No. 12 Richard Gasquet defeated Denis Istomin 7-5, 7-6 (5), 6-4. ... No. 25 Ivo Karlovic took out Jarkko Nieminen 6-4, 6-4, 3-6, 6-4. ... No. 15 Fabio Fognini defeated Andrey Golubev 6-4, 6-4, 6-2.