Eight months after back surgery, Murray is finally feeling good about things, virtually pain free and hitting with the comfort he was at times denied during the previous 18 months.
Even when he arrived in Paris, Murray was not entirely sure how he would hold up physically, how the demands of five-set tennis on the toughest surface of all would affect his body. However, the manner of his display against Fernando Verdasco in the previous round, when he attacked from the off, has convinced the Scot that he is very close to being in the best possible shape for Wimbledon, which begins a fortnight on Monday.
"The way I'm hitting my backhand now is 10 times better than it was last year," said Murray as he contemplated his match with Monfils. "Moving to that side as well is so much better than it was.
"There were periods this year when I had some problems, but that is to be expected with surgery and it's starting to get better slowly and I'm close to being 100 per cent. That's exciting for me especially at this stage of the year.
"I was in a lot of pain for a long time. It was frustrating, tiring, at times it can make you very angry because I normally enjoy all the training that goes with it but there were periods when it would become difficult. I'd try to push hard and it would hurt and so I'd have to ease off and I couldn't get myself into the shape I wanted to be in.
"So hopefully now I'm over the worst and, so long as I keep monitoring it and doing all the right things with it, I'll be fine."
In the first few rounds in Paris, Murray looked a little unsure of himself, playing well enough but clutching at various parts of his body and gesticulating, more even than normal, towards his team in the stands.
However, something clicked in the latter stages against Philipp Kohlschreiber and, having recovered physically from the 12-10 finish, Murray intimated that he now feels ready to give his all against Monfils.
"The beginning of the tournament is always tricky," he said. "I hadn't played loads of matches coming in and I hadn't been here last year [so] I was a bit apprehensive. I really wanted to do well.
"After I got through against Kohlschreiber, I settled down a little bit and was able to play more freely against Verdasco, more aggressive. In the quarters of a grand slam, if I play as I did today, I will give myself a good chance of winning, so, a good position to be in."
Murray has now reached the quarter-final stage or better in his past 13 grand slams, a statistic bettered only by Novak Djokovic, who has achieved the feat in 20.
It is now eight years since Murray and Monfils played in the first round in Paris, a match which went to five sets but ended in a bit of a farce when Murray was unable to move as a result of injury.
The pair have been friendly throughout their careers, having first played in a junior tournament in Tarbes, France, when Murray was 10 and Monfils 11.
"I remember more he played my brother [Jamie] in the final of the tournament," Murray said. "I lost to him in the semi-finals. My brother beat him in the final.
"He used to play with glasses. He had sort of like shaved hair, but quite a high cut. He was the same as he is now; he was just a great athlete, moved unbelievably well, smiling on the court, enjoyed playing in front of a crowd. He's just always been a great entertainer and he's great for the sport."
Murray has played several Frenchmen in Paris and will be on the stadium court tomorrow, while eight-time champion Rafael Nadal is consigned to Court Suzanne Lenglen for his match with David Ferrer.
"I'm not expecting the crowd to be for me and I look forward to that as it doesn't happen [often] when the whole crowd is against you," added Murray. "Even in Davis Cup in Italy, we had great support there so it's going to be a good experience."
Djokovic, meanwhile, took another step closer to a victory that would give him the career grand slam, beating Milos Raonic of Canada 7-5, 7-6, 6-4. Raonic, in his first grand slam quarter-final, banged down 19 aces but the Serb just had too much for him when it mattered.
His opponent will be No.18 seed Ernests Gulbis, who followed up his win over Roger Federer in the previous round by crushing sixth seed Tomas Berdych 6-3, 6-2, 6-4.
Until now, the Latvian has been better known for his colourful personality, rich father and a rather busy social life. However, Gulbis has shown against Federer and then Berdych that he is among the most talented players on Tour and will fancy his chances even against a rampant Djokovic.