The Tinkoff-Saxo rider was out-numbered on the Stage 15 finale with rival Fabio Aru supported by Astana team-mate Mikel Landa who went on to claim the stage victory on the Madonna Di Campiglio.
The final climb, 15.5km long, which rose to around 6.5 per cent, began with Astana outnumbering Contador five to one but the Giro leader was untroubled in handling anything thrown at him by the superiour numbers on show.
Contador was able to extract another seven seconds from Aru to extend his lead to 2min 35sec with six stages remaining.
“Everyone would like to win a Giro stage, especially on a climb like Madonna di Campiglio, but the race situation was complicated," said Contador.
"The gradient wasn't exceptionally steep, which made it complicated, and (Mikel) Landa was very good, so it wasn't to be. There is still a long way to go, and everyone has good days and less good days. Today, Landa was stronger than Aru - that much was clear. But, as I said yesterday, I have to look carefully at each stage and, perhaps, instead of defending, attack, if my legs allow it."
Monday is the second and final rest day of the tour, with the race again tackling the high mountains on Stage 16 with 174km from Pinzolo to Aprica.