Roger Federer would have won more Grand Slams if not for Novak Djokovic, according to the former's ex-coach Stefan Edberg.

Federer is experiencing a career resurgence, having won a total of nine titles since returning from injury at the start of last year — including two Australian Open crowns and an eighth Wimbledon victory to take his tally to 20 Grand Slams.

Earlier this year, the Swiss legend also returned to the top of the ATP rankings, making tennis history as the oldest ever No. 1. With the grass-court season commencing this week, Federer will be looking to thrive once again on his preferred surface and win a ninth Wimbledon title next month.

While his current success at the age of 36 is a remarkable thing to witness for the sporting world, his coach from 2014 to 2015 Edberg believes his Grand Slam tally would have been even greater if he didn't have to face Djokovic.

Before his win in last year's Australian Open, Federer underwent a near-five year drought with his last major title coming at Wimbledon in 2012. In the following five years, he would come close on many occasions only to lose with Djokovic, who notably defeated him in their last four Grand Slam meetings, including two Wimbledon finals in 2014 and 2015 and the 2015 US Open final. 

"When I joined his [Federer] team, I felt he could win a Grand Slam," Edberg said, as per Express. "He deserved to win a title in 2014 and 2015, but Novak Djokovic was a bit better.  As you get older, it obviously becomes tougher. But Roger is absolutely without time. What he did in the last years is incredible. Two or three years ago he was a little bit unlucky with majors."

"At the 2017 Australian Open he had the necessary luck. The balls that before went out now were falling on lines. His confidence increased and in the end, he won Wimbledon and Australian Open. I don't think that anyone believed he could do it at his age. He may have reduced his expectations, so he got relaxed. Roger is unique in many ways: on the court, but also in treating media and fans."

Djokovic last defeated Federer in the 2016 Australian Open semifinals which marked seven wins in their last 10 meetings, but the pair have not met since then with the former having a downturn in form since the start of last year due to injury, coinciding with the latter's career renaissance.

The Serbian showed major signs of improvement during the clay-court season however, and due to his current No. 21 ranking, could face Federer early on at Wimbledon which is a prospect the Basel native is looking forward to.

"Then you also have [Marin] Cilic, [Juan Martin] Del Potro and, I hope, Novak [Djokovic] will come back strong," Federer said this week of potential threats at Wimbledon. "He has already shown good tennis this year."