For Roger Federer, winning grand slams is like riding a bike. Once you know how to do it, you can do it again.
The evergreen Swiss may be carrying a bit more baggage these days, not least with his four children in tow, but in his 60th successive grand slam, the 33-year-old truly believes he can extend his record tally of singles titles to 18.
Twelve months ago and nursing a back injury at the US Open, Federer was upset by Spain's Tommy Robredo in the fourth round at the year's final grand slam.
A year on and the Swiss second seed faces Australia's world number 76 Marinko Matosevic under the lights at Flushing Meadows on Tuesday, confident he is in good enough shape to win again.
"I think last year I was trying to convince myself I did have an opportunity," said Federer, who reached the Wimbledon final last month. "The confidence was going away quickly just because I was just not moving so well.
"This year, really from the first week, I have always played really nice tennis. So you come into this US Open and you remember how it feels to win tournaments.
"You almost forget how to lose to a point and confidence rises. You're back to winning ways again and everything seems so simple. I really feel like I can play a great tournament."
Following Federer onto Arthur Ashe Stadium court will be Serena Williams, who begins her quest for a third straight US Open title against another American, teenager Taylor Townsend.
Wimbledon champion Petra Kvitova takes on Kristina Mladenovic of France while runner-up Eugenie Bouchard of Canada faces Belarussian Olga Govortsova."