Holger Rune may have never played against Carlos Alcaraz on clay but still issued massive praise on the Spaniard at the start of the clay season, declaring him “the toughest” opponent on the slowest tennis surface.

For two decades, Rafael Nadal had been considered by far the most dominant force on clay. But the record 14-time French Open champion is retired now and during pressers in Monte Carlo, the media has been trying to figure out who’s the best clay-courter right now.

Rune, ranked at No. 12 in the world, thinks it’s reigning French Open champion Alcaraz.

“I think the toughest one might be Alcaraz. Let’s see how his form is beginning of the clay season, but he’s a guy when he hits his best level — I think he’s possibly the best in the world. I think he can definitely bring a big challenge. The last years he was injured and stuff here, so he hasn’t gotten the experience like other players here, but I’m sure he will eventually,” the Dane said when asked to name the toughest to play on the dirt.

Rune’s statement about Alcaraz’s makes sense

At 21, the Spanish tennis star has a French Open title in his collection – two Madrid Masters trophies – three clay titles at the ATP 500 level – and also two ATP 250 titles. And since seven of his 17 titles have come on the dirt, that makes clay his most successful surface.

Meanwhile, Alcaraz off to a good start at the Monte Carlo Masters, where he beat Francisco Cerundolo 3-6 6-0 6-1 before also annihilating Daniel Altmaier 6-3 6-1. In the Monte Carlo quarterfinal, the No. 2 seed will play against Arthur Fils.

The 21-year-old Spaniard is playing in the Principality for only the second time in his career. In his debut which came three years ago, he was beaten by Sebastian Korda in his opening match.

Since Rune retired in the first round to Nuno Borges, Alcaraz won’t be meeting the Dane in Monte Carlo.