Rafael Nadal and Dominic Thiem will use their highly anticipated semifinal meeting at Barcelona on Saturday to assess their level following shaky starts to the clay-court season.

Nadal, returning from a knee injury, fell tamely in the semifinals of Monte Carlo to Fabio Fognini, while Thiem, who won his first ATP Masters 1000 title in Indian Wells, dropped his opener at the tournament.

"It will be incredible complicated," Thiem told press at Barcelona. "It's a tournament he's won 11 times and he will have the support of the Spanish crowds. But we've played some amazing matches."

Nadal has a 8-3 head-to-head lead over the 25-year-old, but Thiem beat him on clay in the Madrid quarterfinals last year and the Rome quarterfinals in 2017.

"I will follow the same tactics as Madrid [in 2018] and Rome two years ago, when I beat him," Thiem said. "I will be very aggressive, because that's the only way to beat him."

Thiem's third career win over Nadal was also on clay, in Buenos Aires in 2016.

On Friday, Nadal said he was happy with his play after his 7-5, 7-5 win over Jan-Lennard Struff in the quarterfinals.

"I felt a positive energy and good attitude and confidence in my game. The more days I am on the courts, the more I will arrive at the desired level," he said. "Playing against someone of Thiem's stature will allow me to play a tough match, which provides security and good feelings."