Pau - Spaniard Alejandro Valverde admitted he was concerned about French veteran Jean-Christophe Peraud in the race to finish on the Tour de France podium.
Valverde remains second overall but has shown weaknesses on the previous two days in the Pyrenees.
And with Thursday's unforgiving 144.5km stage 18 to come, with the behemoths of the Tourmalet and Hautacam mountains to climb, Valverde acknowledged that he was in a precarious position.
"Thursday will be a very hard day, especially after the last two days," said the 34-year-old Movistar leader.
"(Thibaut) Pinot and Peraud are very close to me in the standings but I'm more worried about Peraud because he's very good in the time-trials."
Valverde has used his vast experience to hold onto second place.
In the Alps he feigned tiredness to get a tow behind Pinot before outsprinting the Frenchman to the line to take some valuable seconds out of the FDJ leader.
Then in Wednesday's Pyrenean stage he used two teammates up the road to pace him back up to the likes of Pinot, Romain Bardet and Tejay Van Garderen having earlier been dropped, before putting in a late burst to take another 5sec out of the trio.
Yet what has been evident is that Valverde is struggling to keep pace and there are three Frenchmen lining up behind him willing to strike.
Pinot looked strong on Tuesday but struggled a bit on Wednesday yet remains third, 34sec behind Valverde and 8sec ahead of Peraud.
The 24-year-old says he still needs another big day in the mountains if he is to finish on the podium in Paris as he expects to lose time to both Peraud and Valverde in Saturday's 54km time-trial.
"I need a good minute's advantage over Peraud and Valverde ahead of the time-trial," he said.
"Nothing's decided for the podium and that's great for the suspense."
Peraud is looking like the best home bet for a podium finish as he is a better time-trialler than Pinot and 23-year-old Bardet, his AG2R teammate.
The 37-year-old has also twice been able to latch onto race leader Vincenzo Nibali's wheel as he accelerated away from his rivals.
"I'm very happy with my form: hanging onto Nibali in the third week! I had the good fortune of having him as a point of reference. He worked with me and I thank him for that," said Peraud, who was ninth at the Tour in 2011, after Wednesday's stage.
The former mountain biker has not had the same attention as young guns Pinot and Bardet but has been getting stronger as the race proceeds.
As for the race leader, who now has a 5:26 gap to Valverde, it is all becoming a little easy.
The 29-year-old Italian even admitted he was riding within himself.
"My condition is very good and I'm ready to push right to the end but when I get to the end of a stage I'm not giving everything because I don't have to, and I've also had an eye on the next stage," said Nibali.
However, he admitted it would have been different had the best riders been there.
Reigning champion Chris Froome crashed out on the fifth stage with a broken hand and wrist while two-time former winner Alberto Contador broke his shinbone in a fall on the 10th stage on Bastille Day.
"If Chris Froome or Alberto were riding I would need to push much more but then I would also have to manage the race differently and play more of a waiting game," added the Astana team leader.
"When they attack they are more explosive so I would have to be careful.
"I have a lot of respect for these riders."