A well taken first-half goal from midfielder Mike Jones proved enough to give John Gregory's men victory at home to Colchester, and Whittingham believes there is no reason why they should not go on a late charge with the games in hand they have on the other clubs in League One.
Whittingham felt Crawley had to "grind out a performance" against the U's but he has no doubt the clean sheet will increase confidence ahead of Tuesday's sell-out home game against top-of-the-table Wolves.
He said: "You have got to look above you to see what is possible. You have only got to look at Sheffield United. Before they went on their run they were losing games left, right and centre, so you have got to believe you can do it.
"We have got to prove we are not a bad outfit. This club has come a long way in a short space of time and we are looking forward to the challenge of facing Wolves on our own ground."
Crawley are currently 14th in the table, 15 points off the play-offs, and Whittingham added: "We've got a lot of games left and a difficult run of fixtures so we have to make sure our energy levels stay high.
"The clean sheet was really important and you can build on this type of display - when you have to grind out a performance."