Martin is currently sixth on the General Classification with three days to go, 2´56” behind race leader Chris Froome (Team Sky) who survived a relentless day of attacks on the final mountain stage of this year´s race.
The 179.5-kilometre contest from Briancon to the top of the Hors Categorie-ranked Izoard was really the last chance for anyone with visions on the yellow jersey to try something.
Most of those in contention for the overall victory in Paris on Sunday tried to unseat Froome and put him under pressure on the final climb, Martin included, but nobody was able to deliver a knockout blow.
Warren Barguil (Team Sunweb) won his second stage of the race after springing clear of the group of 54 riders he was in from the very outset.
The Frenchman edged Darwin Atapuma (UAE Emirates) who hung on for second while behind, a real GC battle was unfolding as the rest of the day´s escapees were reeled in one by one, including Ireland´s Nicolas Roche (BMC Racing Team).
Frenchman Romain Bardet clawed back four seconds in bonus time as he pipped Froome to third place on stage 18 but Froome emerged from the final mountain test of the race with a 23-second cushion in yellow.
With a relatively flat stage to Salon-de-Provence to follow today before a time trial in Marseille that should suit Froome, his rivals are all-but out of opportunities to deny him.
“I wouldn’t say it is quite won yet but certainly the toughest part of the Tour with the Alps and the Pyrenees is done now,” Team Sky’s Froome said.
“I’m pretty happy to have got through the Alps much better than in previous years because I’ve always struggled in the Alps.”
Bardet sits second overall with Rigoberto Uran third, 29 seconds down, and it is perhaps the Colombian who poses the bigger threat given his track record in time trials. That said, the Cannondale-Drapac rider conceded 61 seconds to Froome in the opening time trial in Dusseldorf almost three weeks ago, compared to 39 by AG2R La Mondiale’s Bardet.
“It’s a really close race for sure,” Froome added. “Hopefully if the first time trial in Dusseldorf is anything to go by, I’ll have the upper hand on the rest of the GC guys. But it’s still very close and anything could happen.”
Martin was active in forcing the pace on the Izoard, and finished within 19 seconds of Bardet and Froome to retain sixth place overall.
“I tried to keep the pressure on Aru, who was suffering. I also wanted to see if I can distance Froome and managed to open a gap, before he came back,” he said.
“I found it strange that no one else attacked, it look like they wanted to protect their places in the GC, but that was their decision.
“From my part, I gave everything I had and I am happy and proud to be here ahead of the final weekend, it’s quite the performance considering my first week crash and the fact many of our guys had to abandon through illness,” he added.
Meanwhile, Roche would finish 33rd on the stage, some 4:59 down and he is now 31st overall.
Today’s stage takes the riders on a 222-kilometre journey and though there are three categorised climbs, it’s likely the main group of favourites will come in together on the same time which should tee up tomorrow’s penultimate stage time-trial in Marseille very nicely.