Roger Federer signalled the start of 2018 pre-season after managing limited schedule in 2017

Roger Federer has begun preparation for the 2018 campaign after the world number two posted an image of himself in the gym with long-time trainer Pierre Paganini.

The Swiss ace had a phenomenal 2017 campaign after struggling with a knee injury in 2016. He won seven titles including two Grand Slams — the Australian Open and Wimbledon this year.

Federer was on course to finish the season as the top ranked player in the world, but a minor back injury scuppered his chances as he was forced to withdraw from the Cincinnati Masters and was not at his best at the US Open. His misfortune was Rafael Nadal's gain as the Spaniard, who also had a brilliant year, took the initiative and took a firm grip on the world number one ranking by winning at Flushing Meadows.

The 36-year-old missed the last six months of the 2016 season due to a knee injury and only returned to competitive action at the start of this year. He immediately went on to win three of the first four tournaments he entered — the Australian Open, the Indian Wells and Miami Masters.

Federer made it clear from the start that remaining fit throughout the entire campaign was his main priority, followed by challenging the major titles. This saw the Swiss tennis legend skip the entire clay court swing of the season, including the French Open, in order to remain fresh for the grass and hard court events that followed.

It paid off as Federer won in Halle and Wimbledon and he has hinted that he could take a similar approach in 2018 in order to avoid the risk of injury. The Swiss tennis legend followed it up with wins at the Shanghai Masters and the Swiss Indoors in his hometown and was keen to end the season with the ATP Finals title in London. But it was not to be as he was beaten in the semi-finals by David Goffin.

After a short break, the Swiss ace now revealed that he has begun his pre-season preparations when he wrote: "Gym time" alongside a picture of him and his trainer on his official Twitter account. Paganini has officially been part of Federer's team for 17 years after first meeting the Swiss star in 1994.

Federer has credited the 59-year-old Swiss fitness coach for his return from a bad knee injury in 2016 when questions were raised about his future in the game. The eight-time Wimbledon winner has since silenced his critics and gone on to have his best season in a decade.

Paganini, on the other hand, believes Federer can continue playing for a number of years as his athletic age is much below his actual age of 36. The duo will combine again to ensure the number two ranked player has another successful and injury free 2018 campaign.