The Eagles were rocked on Wednesday night when they were informed Rioli had returned an adverse analytical finding for urine substitution in a routine ASADA test.

Rioli faces a ban of up to four years - an outcome that could potentially end what seemed set to be a glittering AFL career.

Cripps has played an important mentoring role for Rioli and Liam Ryan, helping develop the talented indigenous pair into two of the most exciting small forwards in the game.

Ryan and Rioli highlighted their importance to the side with star displays in last week's 55-point elimination final demolition of Essendon.

Ryan booted three goals in another flashy performance.

Rioli, who will miss the rest of the finals series after being provisionally suspended, finished with one goal and two score assists from 15 disposals.

Ryan and Rioli are close friends, and it remains to be seen how much the drama will rock Ryan ahead of Friday night's semi-final against Geelong at the MCG.

The guidance of Cripps and indigenous leader Lewis Jetta is set to prove crucial in helping ensure the devastation doesn't reach epic proportions.

Speaking a week before Rioli's provisional ban was handed down, Cripps expressed his awe at watching Rioli and Ryan in action, and his pride at being able to help them achieve their goals.

"It's awesome to learn a few things off them, and awesome to try to help them out," Cripps said.

"Being the older one of the small forwards, I try to show leadership to them. I've enjoyed playing with them.

"It's exciting, because you don't know what they're going to do half the time. It's unpredictable. It's good to watch them.

"I'm glad they're on my team."

Rioli had to lose a staggering 16kg just to get his chance on an AFL list, and he fulfilled a boyhood dream when he became a premiership player last year.

The 24-year-old's story was an inspiration for others, and he is one of the most popular personalities at West Coast.

His honesty and genuine care for others have shone through during his time at the Eagles, but his career is now at the crossroads.

Rioli spoke recently of the importance Cripps has had on both his and Ryan's AFL career.

"The reason we're playing good footy is because Crippa's been helping us a lot off the field, putting us in the right spaces and showing us how to run," Rioli said at the time.

"A lot of people (outside the club) probably don't rate him as much, but he's one of the best at our position.

"We're just learning from him. I couldn't ask for a better mentor. He's always there when I need him."

Cripps was diagnosed with type 1 diabetes just before the 2010 national draft.

He kept the diagnosis a secret until the Saints snared him with pick No.24.

Cripps was traded to West Coast two years later, and he has steadily improved to the point where he is now among the elite small forwards in the competition.

"When I got here he was still pretty young and raw," Eagles coach Adam Simpson said.

"Everything he's got to now is just through hard work.

"He's been a massive asset to Willie and Liam.

"They have the talent, but now they've also got the work ethic. That's off the back of Jamie and what he leads with."

Cripps is often mesmerised by Rioli and Ryan.

And he feels the same way when he watches ruckman Nic Naitanui in action.

Naitanui has missed the past three finals series through knee injuries, but made a successful return from an ankle setback in last week's win over Essendon.

At one stage, Naitanui reached a speed of 31.7km/h to run down Essendon speedster Adam Saad.

"Nic would probably be the quickest in our team," Cripps says.

"It's good to see him get a bit of speed up after the injury.

"He was awesome competing in the ruck, hitting it down the mids' throats.

"You just stop and watch him sometimes."

Australian Associated Press