Novak Djokovic began his ascent towards the final grand slam title of the year with an all too easy win against Brazil's Joao Souza whilst elsewhere Rafa Nadal overcame a spirited Borna Coric, Marin Cilic defeated Guido Pella but his fellow finalist last year lost as Kei Nishikori was defeated by Benoit Paire in five sets.
A stroll in the park for Djokovic
The dominant world number one Novak Djokovic barely left first gear as he swept aside the challenge Joao Souza in front of a barely full Arthur Ashe. On the final match of the day schedule, Djokovic battered aside a flustered looking Souza who never looked like threatening the world number one.
In three straight sets, the Brazilian only mustered three games and was routinely broken throughout as Djokovic swung his racket freely, much to the delight of the crowd.
In each set, Souza won his opening service game before being broken to ease in the rest as Djokovic stepped out of first gear and dominated. He was barely tested on his serve and didn't allow Souza to settle on his own.
Andreas Haider-Muller should present a sterner test for the Serb, as the Austian upset the talented Vasek Pospisil in a five set thriller.
Nadal gets off to a good start whilst Marin Cilic begins defence in style
Much has been said of the poor form of a fully fit Rafael Nadal during a testing 2015, but the once dominant Spaniard dismantled the young Borna Coric on the Arthur Ashe stadium to get begin his US Open in style.
Showing glimpses of his former self with huge forehand winners and heart-stopping defence, Nadal hit a massive 40 winners against a young opponent who produced a spirited challenge throughout. But Nadal would have too much for Coric as he eventually sealed the match in four sets.
He will be joined in the second round by reiging champion Marin Cilic who faced had to work to beat Guido Pella. Cilic, who became the first US Open male champion for over ten years to not open his defence on the Arthur Ashe stadium, looked to be cruising after dominating the first set but would have to work hard for the straight sets win. With Pella stepping up a gear and Cilic looking troubled, the hard hitting Croat eventually squeezed through two tie breaks to set up a match against Evgeny Donsky of Russia.
But there was to be no such luck for Nei Nishikori whom Cilic defeated in last year's surprise final, as the fourth seeded Nishikori threw away match points to lose to Benoit Paire of France and become the highest seeded casualty on day one.
Tsonga, Raonic, Dimitrov and Ferrer cruise
Elsewhere a number of seeded players comfortably strolled through their matches to avoid more upsets on day one. Jo Wilfried Tsonga, the loveable Frenchman, defeated Finland's Jarkko Neiminem in three sets to condem Neiminem to his final defeat in his grand slam career as he is set to retire after the Stockholm Open in the autumn.
And two of the most touted players from 2014, who have both endured a stop-start year, Milos Raonic and Grigor Dimitrov looked in good form as they defeated Tim Smyczek and Matt Ebden, respectively, to make it into the second round. They will be joined by former world number four, David Ferrer, who survived from a set down to defeat Radu Albot of Moldova.
But the day's brightest news came from the Grandstand, where
Mardy Fish won the opening game of his final tournament as a player.
Before his final match he tweeted, 'As I start my last tournament, I'm overwhelmed how many people I have to thank. I'm so excited to play the @usopen one last time,' (@MardyFish).
Fish, who has been dogged by mental and physical injuries for several years and last played a grand slam match in 2012, survived from a set down to beat Marco Cecchinato of Italy and will face Feliciano Lopez in the second round.
Selected ATP Results
N Djokovic (1) d J Souza 6-1 6-1 6-1
R Nadal (8) d B Coric 6-3 6-2 4-6 6-4
B Paire d K Nishikori (4) 6-4 3-6 4-6 7-6 (6) 6-4
M Cilic (9) d G Pella 6-3 7-6 (3) 7-6 (3)
J Tsonga (19) d J Nieminen 6-3 6-1 6-1
D Ferrer (7) d R Albot 4-6 7-5 6-1 6-0
M Fish d M Cecchinato 6-7 (5) 6-3 6-1 6-3
J Marchenko d G Monfils (16) 2-6 6-4 5-0 Ret.
M Raonic (10) d T Smyczek 6-4 7-6 (8) 6-1
G Dimitrov (17) d M Ebden 6-4 6-2 6-4