He gained 14 seconds on Froome and his rivals in the Massif Central stage 15 to Le Puy-en-Velay on Sunday with a late attack. His solo move, at 5.7 kilometres to race, saw him overtake Sky's Mikel Landa for fifth place overall.
"I think it works in my favour that there are so many guys close on GC," Martin said warming down outside the team's blue and white bus.
"They look at each other and I am a little further back. They are not [as] wary of me, but I am closer now."
Martin is closer, sitting 1-12 minutes behind leader Chris Froome (Sky) in the overall.
"I very rarely make a plan, it is just opportunities. When Simon Yates attacked on the climb, after he kind of stalled, and I was a bit afraid because the in the race there were many teammates left [of other riders] an Ag2r rider and Landa was there for Chris Froome,” continued Martin.
"I knew it was downhill to the finish, I thought if I go and get a gap then it would be difficult to get back for them. I took the opportunity, saw the opening and went."
A similar move with Yates in stage 13 to Foix saw Martin gain nine seconds.
Watch: Tour de France 2017 stage 15 highlights
"I have been nipping away at time and taking advantage of the situations. I learned the hard way last year that every second counts."
Martin in 2016 slipped back to ninth in the final week. He said earlier that he "raced like an idiot last year and made mistakes in his first year racing for the Tour's overall classification".
The 30-year-old, who is out of contact at the end of 2017, says he does not think about being considered a hero with his attacks.
"I just race my bike. I don't pay attention to that. I just do what I love," he added. "That's why I race the way I do, I just see the advantage and race hard."
The hard part is to come in the coming week after the second and final rest day tomorrow. The peloton faces a stage over the Galibier and one summit finish, never before used, to the Col d'Izoard. The penultimate stage time trial covers 22.5 kilometres in Marseille.
"It's up to everybody else to attack Chris Froome, but as I say, if you have a bad day on the Galibier or Izoard you can lose minutes," Martin said.
"I think everybody is going to be very wary of that and it could lead to a negative race, but having said that, guys do want to win the Tour de France. It's going to be an interesting week."
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