Stan Wawrinka
Stan Wawrinka of Switzerland serves to Philipp Kohlschreiber of Germany during their ATP tennis match at Dubai Duty Free Tennis Championships February 25, 2016. Reuters/Ahmed Jadallah

Stan Wawrinka has joined fellow Swiss Roger Federer and world No. 5 Rafael Nadal in preparing for the grueling competition the clay-court season brings.

Wawrinka, who kick starts his clay-season campaign at the Monte Carlo Masters next week, has joined Nadal and Federer preparing for the ATP 1000 Masters in Monaco. The world No. 4 posted a picture on Twitter earlier this week, hitting practice sessions on clay-court for the first time this season.

After a promising start in the 2016 season, winning the Dubai Tennis Championships and Chennai Open, Wawrinka struggled to maintain his level of play. In his last two tournaments, the Swiss suffered early rounds losses against David Goffin in Indian Wells, and Andrey Kuznetsov at the Miami Open.

But despite the recent setbacks, Wawrinka is convinced he is at par with tennis’ Big Four. Wawrinka insisted that he could beat any of them in big tournaments, just like what he did when he defeated Novak Djokovic in last year’s Roland Garros for the Swiss’ second Grand Slam win.

"I've been in the top 4 or 3 for two years now, I've won two Grand Slams, during that time Nadal has won one, Federer and Murray none and Djokovic has cleaned up the rest,” Wawrinka told Tennis Now. “My place is there, but I've no intention of messing with that particular legend. I'm not one of the Big Four. But I know that I can beat any one of them at the big tournaments. I know that for a fact, because I've already done it.”

Wawrinka has recorded significant amounts of victories over his Big Four rivals. Throughout his career, the Swiss No. 2 won three matches against Rafael Nadal, seven against Andy Murray, three against Roger Federer and four against Djokovic.

At the Monte Carlo Masters, Wawrinka will get to test whether he could defend his French Open title against the likes of the Big Four, who, for the second time this season, will all be present at a tournament.