From borderline depression to dazzling again, self-confessed Alexei Popyrin 2.0 has made an electrifying start to his career reset with a stunning first-round US Open triumph.

Two days after revealing he’d been such a “wreck” that he’d turned to Oscar Piastri’s mindset coach for desperate help, Popyrin returned to his happiest grand slam hunting ground to claim another prized scalp.

Popyrin ended Grigor Dimitrov’s own inspired run from qualifying to join four Australians in the Open’s second round with a 3-6 6-3 6-2 6-4 win over the former US semi-finalist, one-time world No.3 and ATP season-ending champion.

“He’s an amazing player. I respect Grigor so much. He did something this week that I was afraid to do and that was to play qualifying,” Popyrin said after being relieved to have vindicated his wildcard entry into the final grand slam of the year.

“I was so nervous leading up to the US Open to maybe have to play qualifying, and he managed to qualify and play.

“He was a top-three player in the world and he’s still playing qualies, which is absolutely ridiculous and something that is incredibly tough to do if you’ve been in the position that he’s been.”

Popyrin’s victory snapped a run of three-straight soul-destroying grand-slam first-round exits, two years after the ex-French Open junior champ took down the great Novak Djokovic in a seismic victory on Arthur Ashe Stadium.

“After Wimbledon, I was a wreck,” Popyrin told AAP last Friday.

“I used to – well, I still do – every time I lose, I think I don’t deserve to have fun. After, I think I don’t deserve to be happy.

“I was worried that I wouldn’t enjoy my wedding (in September) because of my tennis.

“And when I had that thought for the first time I was like, ‘OK, something is really, really wrong and I’ve really got to take some time and figure things out’.”

Popyrin sure figured things out on Monday night, slamming down 11 aces, clubbing 33 winners and breaking the Bulgarian six times to set up a second-round clash with Chile’s Alejandro Tabilo.

“I’m trying to not associate my results with how I feel as a person,” Popyrin said before facing Dimitrov.

“I’m trying to look at it in a way that it’s just a journey that I’m on. Where I am is where I am and what I have to do is just continue trusting the process that I’m on.

“I’ve stuck with the same team and I haven’t changed anything. I believe in the guys. I believe in myself. I believe that everything is just mental for me.

“And if I’m able to make those changes up in my head, then I’m able to not only get to where I am, but I believe I can go further.

“I’ve got to kind of start from scratch, which is never easy.”