Read & Watch: Stan's Plan Again Stumps Dimitrov
And for the second consecutive major, Wawrinka defeated reigning Nitto ATP Finals champion Grigor Dimitrov in a mouthwatering championship opener. The 2016 titlist overcame the eighth seed 6-3, 6-2, 7-5 after two hours and 24 minutes to level his FedEx ATP Head2Head series against the Bulgarian at 4-4 and advance to the second round.
"Two years ago was something very special, of course, [I have] amazing memories after the final... So it was great to come back, that is for sure," said Wawrinka.
Wawrinka hit 30 winners, including six aces, to emerge victorious and hand Dimitrov back-to-back first-round Grand Slam exits for the first time in over five years. Earlier this season at Wimbledon, the Swiss recovered from a set down to eliminate Dimitrov 1-6, 7-6(3), 7-6(5), 6-4.
"For sure, it was a tough match," said Wawrinka. "I knew it would be a difficult match. Playing the first round in a Grand Slam, you need to be ready for it. You need to play [your] best tennis from the first point.
"We played already in Wimbledon, so it was a surprise again to play each other. But I'm really happy, first with the victory, that is for sure, but with my level in general."
The 33-year-old has won 39 of his 50 matches at Flushing Meadows, including each of his eight most recent encounters. Wawrinka has reached the quarter-finals or better in each of his four appearances at the event since 2013.
With three service breaks to none in the opening two sets, Wawrinka quickly established control of the match. The Western & Southern Open quarter-finalist showed signs of his best form, building on his strong performances at recent ATP World Tour Masters 1000 events in Toronto and Cincinnati.
"I have been playing some good tournaments, Cincinnati and Toronto, and keep improving there day-by-day," said Wawrinka." I arrived here a week early to practise, get a lot of time on the court, and I'm happy with today's match. I think it's a great start."
The third set proved to be much tougher for the Swiss, who finally dropped serve in the eighth game after saving his first seven break points of the encounter. Wawrinka quickly responded as Dimitrov served for the set at 5-3, stepping up his aggression to immediately break back, before holding serve for 5-5.
The momentum had clearly swung back in Wawrinka's favour. The three-time Grand Slam titlist secured a second straight break with conviction on his forehand side. In the following game, Wawrinka served out the match to 15, sealing victory with his sixth ace of the match.
Dimitrov drops to 8-8 at the US Open. The 27-year-old's best performances at the USTA Billie Jean King National Tennis Center came in 2014 and 2016, losing in the Round of 16 to Gael Monfils and Andy Murray, respectively.
Milos Raonic overcame a spirited challenge from Argentine Carlos Berlocq 7-6(4), 6-4, 1-6, 6-3 to reach the second round. The Canadian, who has reached the Round of 16 on three occasions (2012-14) in New York, hit 63 winners and won 91 per cent of first-serve points to beat the 35-year-old in two hours and 41 minutes.
"I had my moments. [I was] a little bit too much up and down and lacked a bit of discipline on my service games," said Raonic. "Otherwise I got the job done and have to be happy with that. When there was pressure on me, I stepped up and I was able to play better in those scenarios."
The Cincinnati quarter-finalist improves to 25-10 at tour-level this season and 3-1 in his FedEx ATPHead2Head series against Berlocq. Raonic will face Gilles Simon in the second round. The Frenchman defeated #NextGenATP South African Lloyd Harris 6-2, 6-3, 6-3 in two hours and 18 minutes.
"I have to be more disciplined [against Simon]," said Raonic. "He is going to let me get into points... but I have just got to be more disciplined from the start and throughout, especially on the serve."
Dusan Lajovic also progressed, recovering from a set down to beat 24th seed Damir Dzumhur 3-6, 6-1, 6-3, 6-4. The 28-year old will meet Great Britain's Cameron Norrie in the second round. Norrie scored an impressive 7-5, 4-6, 6-4, 6-3 win over Jordan Thompson to reach the second round for the second year in a row.