La Toussuire - Nairo Quintana admitted he was surprised at how little time Chris Froome lost after the Colombian attacked the Tour de France leader on Friday.
Quintana finished second on the 138km 19th stage from Saint Jean de Maurienne to La Toussuire and gained 30sec on Froome after attacking his rival 5.5km from the finish.
But he had been hoping his move would do more damage.
"On the whole the day went pretty well but we just lacked the final touch," said the 25-year-old Colombian, who sits second overall at 2min 38sec with just Saturday's final Alpine stage left to overhaul Froome.
"I tried to find the best moment to put a good amount of time and distance into Froome but in the end he defended well and I only gained a small amount of time.
"I thought today the time gaps would be greater. We did what we thought we had to do but he defended very well.
"He was still strong and tomorrow (Saturday) we'll try again, although certainly from further out, and we'll also try to win the stage."
Quintana said he couldn't attack sooner because Alberto Contador's Tinkoff-Saxo team were riding too hard on the front of the peloton.
"Saxo's tempo was quite high and it would have been foolish to attack because we wouldn't have gained much time and in the end we attacked when we thought we could do the most damage.
"We'll keep fighting and if there's the chance we'll try again (on Saturday)."
Froome said Quintana is now the only threat to his hopes of reclaiming the title he won in 2013.
And the 30-year-old Briton said he had managed the time loss so as not to hit the wall.
"At this stage I really think it's about following Nairo - he showed today that he obviously still has very good legs," said Froome.
"When he went, I just went into timetrial mode. I thought, 'I've still got a 3min 10sec advantage, I don't need to panic, but I do need to keep something in reserve for tomorrow'.
"At this stage he's the guy for me to look out for."