Roger Federer admitted he was not surprised to see Novak Djokovic struggle to get back to his best after the Serbian was knocked out in the second round of the ongoing Indian Wells Masters Series in California.

It was Djokovic’s first appearance since the Australian Open after undergoing a minor surgery to repair an ongoing elbow injury, but it lasted just two and a half hours as he was knocked out by the 109th ranked Japanese 7-6, 4-6, 6-1.

The former world number one has struggled with an elbow injury since the 2017 Wimbledon Championship. Djokovic missed the last five months of the previous campaign to recover from his injury, but was unable to get back to his best despite months of rehabilitation.

Federer is no stranger to injury after missing the last six months of the 2016 season with a knee injury, but the Swiss ace’s comeback was far from a struggle. He has been playing some of the best tennis of his career since his return which has yielded him nine titles in the last 13 months.

However, he is aware of the struggles players endure while returning from a long-term absence and believes Djokovic is only ‘going to get better’ as the season progresses. However, apart from the physical struggles Federer had to face questions about his future in the sport during his absence, which is not the same for the Serb.

“To me, it's not that surprising," Federer said, as quoted by Sky Sports. "When you go away from the game for over a two-month period, it starts feeling a little bit that way.”

"When you do come back from injury or when you haven't played in a long time, it just takes extra effort. It is still early stages for Novak coming back and the first one after surgery. He's only going to get better from here,” he added.

The 36-year-old had failed to win a Grand Slam title since 2012 when he decided to end his season after Wimbledon in July, 2016, which raised a number of questions about his future in the game. A number of former players and experts doubted if Federer could get back to his best and called for him to call time on his illustrious career.

The Swiss legend however had other ideas, he returned to action at the start of the 2017 season and silenced his critics in the best way possible. Federer displayed a new brand of aggressive tennis and went on to dominate the tour claiming seven titles which included two Grand Slams.

He has carried that form into 2018 and is currently unbeaten this year, having made it 20 men’s singles major titles following his Australian Open triumph in January. Federer revealed that the thought of retirement never crossed his mind during his time out with a knee injury.

“It was never — ‘What do you guys think? Is this over? I never had that,” Federer said, as quoted by the Express. “I felt I was too close to winning.”

“I was too close to the top. I was too close to still beating the best,” he said.

Federer, however, is unsure if his record of 20 Grand Slam titles will remain intact suggesting long-time rival Rafael Nadal could stake his claim if he has a good run before he retires. The Spaniard, who is currently injured, has 16 major titles to his name with 10 of them coming at the French Open.

Nadal is five years Federer’s junior and thus is likely to play longer than the Swiss and Federer believes records were safer in the previous era. Pete Sampras’ Grand Slam record of 14 titles stood for seven years before it was eclipsed by the current ATP men’s singles world number one.

“No, not at all,” Federer said when asked if his Grand Slam record was safe from Nadal’s grasp. “I just feel like today we’re all so good on clay, grass, and hard courts, if you get on a roll you can rack up some titles.”

“It’s not as safe as it was in, say, the 1980s,” he added.