The Spaniard was forced to pull out of la Roja's squad after suffering a thigh knock against Finland on Friday, while the Brazilian has been out of action with a hamstring tear.
And while Montoya is normally employed at right back, he would be happy to fill in on the left-hand side of the field if required.
"I have played three or four games in that position and it is almost the same as to playing on the other side," he told reporters. "I feel pretty good about it. I have no problem with being on the left and I think I can play there."
Montoya helped Spain Under-21 overcome Russia, and the 21-year-old was happy both on a personal level and with the team's performance.
"The Russian team were more difficult than Norway, who we played last Thursday [Spain won 5-2] and personally I felt very good. Physically I felt exceptional and I am very happy with how the game went," he stated.