
Nadal was severely tested by Thiem, who shocked him in a Buenos Airessemi-final two months ago and who was playing his 33rd match of theseason. The 14th-ranked youngster stands 26-7 overall in 2016; helost only his second match since February on clay.
Nadal was put to the sword by the aggressive Thiem, with the Spaniardfighting off 15 break points from 17 chances - almost all of them inthe marathon opening set which ran for 80 minutes
The 12th-seeded Thiem lost to Nadal for the first time since RolandGarros two years ago, with the match ending after just over twohours.
Nadal improved to 55-4 over his career in Monte Carlo, the venuewhere he claimed eight straight titles from 2005-2012. His victorymarked his 14th of the season against six defeats. The winner next plays fellow French Open champion Stan Wawrinka afterthe Swiss fourth seed easily accounted for Gilles Simon 6-1, 6-2.
Second seed Andy Murray needed to struggle to get past quirkyFrenchman Benoit Paire, with the Scot beating the 16th seed 2-6, 7-5,7-5.
Murray, constant berating himself during a frustrating effort on theclay, trailed a set and two breaks before patching together avictory.
"It was a big win coming from 6-2, 3-0 down, two breaks, when you'renot playing particularly well, it's a great effort," he said.
"These matches are important. It would have been easy to lose todayand get down on myself. But I kept fighting right the way through tothe end. It was a good one to get through because I could have easilylost today."
Murray will next line up against Milos Raonic after the Canadiantenth seed was treated on his troublesome right thigh in a 6-3, 4-6,7-6 (7-5) third round defeat of Bosnian Damir Dzumhur.
Murray owns a 5-4 record against Raonic, whom he beat in anAustralian Open semi-final.
The Scot who has not won a trophy this season, needs to sort out hisclay form as he defends titles form Munich and Madrid later in thespring during the run-up to the May 22 start at Roland Garros.
Murray is the tournament's highest-ranked seed after the second-roundelimination of Novak Djokovic.