Playing his first match at the tournament since he was accused of tanking by John McEnroe in a dispirited loss to Andy Roddick last year, the Australian fought where previously he had surrendered.
Tomic's 6-3 3-6 4-6 7-6(1) 6-3 victory moved him into a second-round clash against world No. 179 Dan Evans. The English qualifier was a surprise 6-4 6-4 6-2 winner over Japan's 11th seed Kei Nishikori in the first real upset of the championships.
"Definitely," Tomic replied when asked if had made amends for the Roddick match.
"To turn any match around like this, where I think I was probably one or two points away from being out of the tournament ... being able to turn that around and find something inside you to win this match was very, very good for me.
"I take that as confidence into my next round.
"Today was all about finding a way to get out. Sometimes you don't need to play really well to win."
The 20-year-old said he was getting used to playing without his coach and father, John, being in the grandstands.
Tomic snr is banned from entering Flushing Meadows in the wake of an assault charge yet to be ruled on by a Spanish court.
"I'm managing now," Tomic said. "It's still difficult, but what can I do?
"I'm trying to play my best, every time I play. I want to get better. That's where my mind is. I'm not looking where my dad is.
"Of course my dad is still on my side ... but I'm trying to find myself, deep down inside and become the best player I can be."
Tomic trailed by a break in the fourth set before levelling at 4-all. Momentum clearly swung to his side and after winning a marathon 17-minute game to lead 3-2 in the fifth, he sailed home against the fatigued and frustrated Ramos.
"Grand Slams, you always want to play your best," Tomic said.
"I dug deep today. It's one of the favourite places for me to play, in these big tournaments, and it gets the best out of me.
"Whether you're down, whether you're up, you always want to give your best. I gave myself a chance, as opposed to quitting."
Tomic said he would search for video footage of the unheralded Evans.
"I like having these sorts of matches at the start of a Grand Slam, takes the pressure off," Tomic said.
"Now the pressure is off me, you know. I'm playing a guy I can beat. I have to come out playing well. And if I do that, I'm looking pretty good.
"But I've got to stay focused and concentrate. Every match is difficult here. Everyone can play...I don't know too much about him but obviously I need to, because he beat a very good player today."
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