BUENOS AIRES (AFP) - Top seed and defending champion Rafael Nadal reached the Argentina Open semi-finals on Friday, braving temperatures of 33 degrees to clinch a 7-6 (7/3), 6-2 win over Italian journeyman Paolo Lorenzi.

Nadal, the world No. 5, is back on his favourite clay court surface and is playing his first event since his shock opening round loss to compatriot Fernando Verdasco at the Australian Open last month.

He had seen off close friend Juan Monaco of Argentina in Thursday's first round but faced a slightly tougher test Friday when 34-year-old Lorenzi, the world 52, clawed his way back from a 4-1 first set deficit.

But 29-year-old Nadal clinched victory on his first match point after one hour and 51 minutes on court.

It was the Spaniard's 346th win on clay as he remains on track to claim a 48th career title on the surface which has brought him his greatest success.

Nadal will now face Austria's world No. 19 Dominic Thiem on Saturday for a place in the final.

Thiem, the fifth seed, defeated Serbia's Dusan Lajovic 6-4, 6-2 in his quarter-final.

Thiem, the youngest player in the Top 20 at 22-years-old, lost to Nadal in their only previous meeting in straight sets at the 2014 French Open.