The Swiss earlier this week said he had sustained a knee problem during the grasscourt season and that he had begun the rehabilitation process with a view to returning to the tour later in the summer.
Federer, who underwent two knee surgeries last year, is in a race against time to win one last Major before he retires. The Swiss maestro can hardly afford another long layoff from the sport at this stage of his career.
In that context, Greg Rusedski suggested Federer might not be motivated to play if he knew his chances of winning were non-existent.
“So the question is, will he be happy not being able to win Majors again, and that is the big question only Roger can answer," Rusedski said on the Tennis Channel.
"Knowing Roger from quite a young age, around 16-17 years of age, I don’t think he will be satisfied just showing up without really believing he can win.”
"Roger Federer has defied logic, he has defied time, he created a new game in 2017" - Greg Rusedski
Rusedski also reminisced about Roger Federer's 2017 season, which saw the Swiss make a winning return to the sport after a serious knee injury.
After missing a majority of the 2016 season due to injury, Federer returned at the Australian Open the following year and defied the odds to win the title at the age of 35. He then went on to lift a record eighth title at Wimbledon and 19th Major overall a few months later.
Rusedski believes Federer's comeback four years ago "defied logic", but questioned whether he would be able to enjoy the same success this time around.
“Roger Federer has defied logic, he has defied time, he created a new game in 2017,” Rusedski said. “There is not more he can create anymore because it was all based on movement, taking the ball early coming forward.”