At 38, Feliciano Lopez has found himself coming up against opponents who are over a decade younger than he is.

This emerging crop of talents play a vastly different game from the one he was familiar with when he started his professional career at 16, but that has served only as motivation for veterans like him to improve and remain competitive.

The Spaniard feels that even with players like Alexander Zverev, 22, Daniil Medvedev, 23, and Stefanos Tsitsipas, 21, establishing themselves in the top 10 in the world rankings, the old guard remains untouchable.

Particularly, the Big Three - Rafael Nadal, 33, Roger Federer, 38, and Novak Djokovic, 32 - who have 55 Grand Slam titles in total.

"Roger is my age and he's No. 3 in the world, he's still fighting against Djokovic and Nadal," said Lopez, the world No. 62.

"It's not normal to see a player at 38 playing. In the case of Roger and Rafael Nadal, it's tough to explain with words how good they are, they have everything."

With tennis becoming an increasingly physical sport, Lopez revealed that the older players had to adjust to the new generation of power baseliners.

For the Toledo native, who achieved his best ranking of world No. 12 in 2015, sustaining a career over two decades means placing more emphasis on his physical fitness as he gets older.

"Fitness condition was very important when I entered my 30s, I needed to be different to still be playing," said the left-hander, whose serve-and-volley style has become a dying art.

"I was travelling with a physical trainer for the past eight years and this was very important because I needed to take care of my body in the best possible way.

"I'm playing more aggressively now than I was playing 10 years ago because the game is changing as before, (there's) always room to improve things to be a better player."

Another thing that has kept him in the game for the past 22 years is his love for the sport.

He said: "When you do something for many years, you need to have this passion and motivation.

"To be honest, I never expected to be still playing at the highest level at my age, but in the last seven or eight years, I've had a lot of success, the level of motivation is very high and this is something that I'm proud of."

Kimberly Kwek