Rafael Nadal and Novak Djokovic admitted that they miss their old rival Roger Federer, who was forced to skip the US Open for the first time since 1999 due to a knee injury.
The 17-time Grand Slam champion ruled himself out of the rest of the season to recover fully from his injury, which got aggravated during his semi-final defeat to Milos Raonic in Wimbledon.
Nadal, who progressed through to the second round, wished his arch-rival Federer speedy recovery and stated that it was very tough to see the players outside of the Tour.
"Roger today is having the same injury issues, so I wish him a fast recovery," Nadal said after beating Denis Istomin to make the second round.
After withdrawing early from the French Open and ruling himself out of Wimbledon due to a wrist problem, the Spaniard had come to Flushing Meadows under an injury cloud.
Meanwhile, World No 1 Novak Djokovic said that every tournament was missing Federer while describing the Swiss maestro as 'one of the most popular players of all time, one of the most successful players of all time'.
"It's not the same when you don't have Roger for the tournament, for the fans. There is no doubt that every tournament is missing him.
"But on the other hand, we have got to focus on the players that we have at the moment. So I think even without him, it's a very strong field. I'm sure it's going to be a good tournament," Djokovic, a first round winner over Jerzy Janowicz on Monday.
Djokovic had defeated Federer in the 2015 US Open men's singles final to win his second trophy at Flushing Meadows.