The Bombers failed to lock up eighth spot on Sunday, surrendering meekly to 14th-placed Fremantle just seven days after they beat the leader-leading St Kilda.
The 54-point loss, coupled with Hawthorn's win over Richmond, sets up a virtual elimination final against the Hawks for the last finals berth.
Knights said Essendon, which hasn't played finals football since 2004, would deserve the opportunity to play in September if it qualifies.
"We've given ourselves an opportunity, and we've still got one more roll of the dice next week to make it happen," Knights said after Sunday's loss.
"I said to the group after the game, a lot of other sides aren't even involved in a big-time match next week to play finals footy, and we are. That's the way we've got to look at it.
"I think the last two weeks we’ve set ourselves up. We'll deserve it if we make it – that's my attitude. If we're not good enough we won’t - if we're good enough, we will.
"We're playing last year's premiers, so if we get over them I think we'll deserve it."
Knights didn’t gloss over Essendon's disappointing effort on Sunday, the side's second loss at Subiaco Oval in a month.
He described the trip west as a failure, and said the side had no answer for dominant Fremantle ruckman Aaron Sandilands, who finished with 42 hit-outs, 21 possessions and a goal.
"We failed today and we're disappointed in our efforts – that's probably all there is to it," the coach said.
"They were a lot more efficient (and) they were a lot more fluent when they had the ball. They got momentum out of the stoppages, and he (Sandilands) was just too much for us to handle today.
"I spoke pretty candidly to the group about how we attacked today and how we were beaten quite convincingly in so many areas of the game.
"The only positive out of today is we've got another opportunity next week to nail that final eight spot against a very good opponent in Hawthorn, who had a very good win against Richmond."
Knights said full forward Matthew Lloyd, who is sidelined with a heel injury, would only play next week if he was 100 per cent fit.
He said the skipper's presence would be "invaluable", but maintained he would not roll the dice with Lloyd, despite the high stakes.
"Lloydy'll be up for selection if he's right to go, but there's no guarantee on that – he's got to complete another two or three training sessions," Knights said.
"He certainly moved a lot better this week and his straight-line running was excellent, (but) he will only play if he's fully fit."
Knights said ruckman Paddy Ryder was an outside chance to take on the Hawks, while Alwyn Davey, who left the ground late against Fremantle with a suspected shoulder injury, would be monitored.
