Following yesterday's 5-1 FA Cup loss to Chelsea, the 31-year-old believes that he and his teammates must "dig in" for the remaining four league games if they are to salvage some success this term.
He said: "Everyone at this present time is doubting us. I have said it to the lads, 'That is when you need to make sure that you are at your best.'
"Even our own fans, and probably even our own manager, doubts us at this moment in time, and we need to stand up and be counted.
"It's clear for everyone to see. If we don't end up fourth this year we will have failed as a squad. We've had a fantastic ride but we've dipped, it's obvious. We need to bounce back. We need to dig in."
Spurs currently occupy fourth place in the Premier League table but are above Newcastle United on goal difference alone.