New York - Five-time champion Roger Federer gets his bid to become the oldest US Open winner in 45 years underway on Tuesday but will be overshadowed by Andy Murray's clash with enfant terrible Nick Kyrgios.
Federer, the second seed who won five years in succession at Flushing Meadows from 2004-2008, starts against Leonardo Mayer, the 34th-ranked Argentine.
The 34-year-old Federer won the pair's only other meeting in Shanghai last year but had to save five match points in the process.
Federer has not been back to a US Open final since losing the 2009 title match to Juan Martin del Potro and was a semi-final loser in 2014.
But he made the Wimbledon final again in July and a victory over Novak Djokovic in the Cincinnati Masters final last month only served to boost his belief that he can add to his 17 majors, the last of which came at the All England Club in 2012.
"I feel like I have a good chance but I really can't think further than my first-round opponent right now," said Federer.
"My focus needs to be not trying to win the tournament right away. That would be thinking too far ahead.
"I haven't been in the final in this tournament as of late. I came close but close is not good enough."
Murray, the 2012 champion, begins his campaign against controversial Australian Kyrgios, the world number 37.
Kyrgios is playing under the shadow of a suspension following his now-infamous, lurid tirade against Stan Wawrinka in Montreal.
Kyrgios was picked up by courtside microphones claiming that compatriot Thanasi Kokkinakis had slept with WTA player Donna Vekic, the girlfriend of Wawrinka.
The Australian was widely condemned for the outburst but Murray has pleaded for patience.
"He's a young guy. He made a mistake. All the guys here when they were 19 or 20 made mistakes. His was seen by millions. It's unfortunate it happened. It was wrong," said Murray of his 20-year-old opponent who he has defeated three times in three meetings.
"I don't think he's a bad guy. He's an unbelievably talented guy with a lot of potential."
Wawrinka, the fifth seed who made the semi-finals in 2013, starts against Spain's Albert Ramos-Vinolas.
In the women's draw, second seed Simona Halep begins against New Zealand's Marina Erakovic, who won a match at the US Open for the first time last year when she stunned former champion Svetlana Kuznetsova.
Halep has yet to get beyond the fourth round at the US Open.
Also in action are former runners-up Caroline Wozniacki and Victoria Azarenka.
Fourth seed Wozniacki faces US college champion Jamie Loeb while Azarenka tackles Lucie Hradecka of the Czech Republic.
Two-time Wimbledon champion Petra Kvitova, seeded fifth, plays Germany's Laura Siegemund.