DON'T write off Nic Naitanui's chances of a fairytale finals comeback yet.

That's the message from coach Adam Simpson and retiring big man Drew Petrie after West Coast snuck into the top eight with victory over the Crows.

The Eagles have booked an elimination final against Port Adelaide next Saturday night at Adelaide Oval, where they have won all three clashes against the Power.

While Naitanui will miss that match, there is hope he could make a stunning return to action if West Coast goes on a deep run into September.

Naitanui hasn't played since round 22 last year due to a knee reconstruction but Simpson has left the door open for a last-minute return.

"He won't be playing (next) week, we'll just put that to bed now," Simpson told Channel Seven on Monday night.

"He's training with the players, he's in really good shape, he's looking really good but to throw him in this week would be pretty silly.

"We've got a good break to recover from the weekend, business as usual tomorrow, we'll get on with Port Adelaide and worry about that (Naitanui's potential comeback) if we win."

The 201cm Eagle's pathway back to football became more difficult at the weekend after East Perth missed out on finals.

But Petrie believes Naitanui could "absolutely" return for West Coast even without a lead-up WAFL appearance under his belt.

"He's been training really well, and he's often training before we get out on the track but we usually see Nic striding up the wing and he gets involved in a lot of the match scenario drills now," Petrie said.

"Nic had a setback I think for about a month in the middle of the year. If that hadn't of occurred, we could almost see him knocking on the door at the moment.

"Unfortunately, East Perth lost on the weekend so there's no chance of him playing WAFL.

"But I think if we go far enough into September, he's likely to play."

Naitanui took part in a skills session on Domain Stadium on Monday and has been back in full training for about a month.

In his and Scott Lycett's absence, Petrie has stepped up and played 14 games in 2017 and forged an invaluable ruck partnership with fellow recruit Nathan Vardy.

There was speculation Petrie could continue on next season, however Simpson revealed after Sunday's win against Adelaide that the 34-year-old 'rookie' would retire at the end of the year.

It was a secret known by very few at the club, including Petrie's teammates.

"It was spontaneous. I just didn't want to rain on Pridda (Matt Priddis) and Mitch's (Sam Mitchell) parade yesterday," Petrie said.

"I didn't want to take anything away from the Subi farewell as well.

"The first thing I did, I apologised to the guys 'I'm sorry boys for not letting you know' firstly … but they heard it when you all heard it."

Petrie, a 16-year veteran at North Melbourne, relished the opportunity to say goodbye to West Coast's fans on an emotion-charged afternoon.

He would be open to joining the star-studded 2017 class of retirees in an MCG motorcade on Grand Final day and could remain in Perth next year, potentially working in the Eagles' football department.

But Petrie's No.1 focus is a looming battle with the Power's spring-heeled ruckman Paddy Ryder, who has torched West Coast twice this year.

"It's one of the hardest challenges rucking against Paddy, he's so agile, so quick, such a good jump, so it's going to be hard to quell his influence on the game," he said.

"We'll do our research, find ways of nullifying him and do our best."