Andrey Rublev believes real tennis is played on the clay surface.

The 25-year-old recently won his first-ever Masters 1000 title at the recently-concluded Monte Carlo Masters. He will now look to win another at the Madrid Open as he takes on three-time Grand Slam winner Stan Wawrinka in the round of 64 on Friday.

That said, having taken so long to win one Masters title, Rublev acknowledges winning two in a row would be pretty difficult to accomplish.

“I think it’s difficult to win two Masters 1000 titles in a row,” Rublev said (via Tennis World USA). “When you’ve been waiting so many years to win one, it would be surreal to win two in a row, but I’ll try to do my best.”

With the clay season in full swing now, Rublev has more or less had a similar win percentage regardless of whether he’s playing on clay, grass or hard court.

However, he believes the true test of tennis is when it’s played on clay.

“The real tennis is played on clay, because it is the surface that requires you to think continuously, to be prepared for long and intense battles, to have a increased physical and mental endurance, and also to be smarter,” he explained. “On hard or fast, everything is more improvised because you hardly have time to think.”

It’s an interesting observation, but one can’t help but wonder if Rublev winning at Monte Carlo may have swayed his opinion that way.

On the flipside, some could argue because you have to improvise more on a faster court such as a hard court, it’s a truer test of one’s tennis ability.

In the end, it all comes down to personal opinion.