“I haven’t played an official match in six weeks. I had to deliver my A-game, which I did I think in the first set.
“In the second, particularly, it was surviving on the court. In the important moments I just put one ball more in the court than he did.”
As Djokovic heads towards retirement, he has continued to scale back his schedule.
The former number one’s focus has been increasingly centred on the Grand Slam tournaments as he aims to land a standalone record 25th major title.
Djokovic skipped the ATP Masters events in Toronto and Cincinnati leading up to the US Open.
In his pre-tournament news conference, Djokovic made a frank admission that he does not “enjoy” the elongated format of the Masters tournaments, which have been stretched to two weeks over recent seasons.
But when it comes to the biggest prizes, his appetite to win Grand Slam tournaments remains undimmed.
Beating the precociously-talented Tien, who is ranked 50th in the world, was Djokovic’s 75th consecutive first-round win at a Grand Slam event – the first singles player to achieve the feat in the Open era to achieve the feat.
“I wish I had Learner’s age – but when you come to the late 30s it’s about learning how to preserve the energy for what matters,” Djokovic said in his on-court interview.
“I still have the flair, I still have the drive, and you guys give me the energy. Hopefully I can keep it going.”