In fact this was his first ever straight sets win against Del Potro, against whom he fought out an epic Rio Olympics final and then lost to in September's pivotal Davis Cup semi-final rubber. After losing to Murray in the first round, Del Potro showed a moment of emotion as he smacked his racquet angrily and slumped on the net before resuming the second round.
"Obviously, this is one of the most important tournaments of the year, I had great memories from last year in Paris and I wanted to come and play some good tennis again".
It was Del Potro's first trip to the French Open in five years, since he received a wrist in 2015 that crippled his playing.
What is Murray's record against Del Potro?
He called for umpire Carlos Bernardes to check and stood for a good minute leaning on the net with head in hands after Bernardes admitted he could not see the mark and stuck with the line judge's call.
"I couldn't believe that I lost that set, because I had many opportunities to win", he said.More news: Why Trump can not fire Federal Bureau of Investigation special counsel Robert Mueller
The pair traded blows in the second set with Murray creeping ahead.
Although Del Potro broke back when Murray served for the second set at 5-4, the Scot forced another break to go 6-5 up and served out the set as the crowd.
This time Murray would make no mistake and crunched it out with his fourth ace of the match.
"I thought I played some good tennis towards the end and I expected a tough match".
The Brit, who struggled to find form during the first half of the season had already played two four-set matches in the first two rounds.
It's a tough match, not an easy third round. "In these conditions, when it's slow and heavy, to be coming back is hard". "You never know when you can win a set or a match, and that happened today".More news: A glance at the Senate's Iran, Russia sanctions legislation
"Yeah, it was obviously an important win for me and a big match, because Juan, when he's playing well, is one of the best players in the world", said Murray. It's the 14th meeting for the pair but just one previous match has come on clay, with Gael Monfils triumphing in straight sets in Barcelona six years ago.
The Swiss world No.3 cruised to victory against an out-of-sorts Fabio Fognini, winning 7-6 (7-2) 6-0 6-2 as the Italian's game fell apart after a strong first set.
The top seed and world number one found himself locked in a ferocious battle in a first set described by Eurosport expert John McEnroe as "one of the best of all time at Roland Garros". I've got to keep taking the initiative to bully players with it when I can.
The 25-year-old Romanian player Halep defeated Russian 26th seed Daria Kasatkina 6-0, 7-5 in the third round in an hour and 18 minutes.
Agnieszka Radwanska, the women's ninth seed, was eliminated in her third-round matchup on Saturday.More news: Portugal forest fire victims die in their cars as flames engulf road
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