SAM MICHAEL doesn't know how long his stint as a top-up player at Essendon will last, and had goosebumps when the opportunity to join the club materialised last week.

But, three hours after touching down in Melbourne after catching a plane from Brisbane, the towering key position player and former Lions ruckman said he hoped his time at Essendon could lead to a return to the AFL.

"I've still got aspirations of playing at the highest level so it's the perfect opportunity for me and [I'm] grateful that Essendon came to me and offered it," Michael said on Wednesday.

The 200cm 21-year-old played three games for the Lions in 2013 before being delisted at the end of last year.

He was due to pull on the boots at the Redland Bombers in the NEAFL this year but will feature in at least Essendon's first two NAB Challenge games next month as a top-up player.

Michael was coached by current Essendon assistant Mark Harvey at the Lions, when the Bombers football boss, Rob Kerr, was list manager.

"I played underneath Mark Harvey in my time at Brisbane and he had a good influence in getting me here in the end," Michael said.

Michael has signed a contract with the Bombers to play for them until March 18, which will include games against St Kilda (March 7) and Greater Western Sydney (March 13).

A decision by the AFL's Anti-Doping Tribunal against the 34 current and former Bombers with infraction notices is expected some time around the club's third NAB Challenge game against Melbourne on March 20.

Michael, who trained alongside the club's VFL squad on Wednesday night after a medical screening, said he would "strongly consider" staying on with the Bombers should they require players during the home and away season.

"At the moment I'm just looking forward to enjoying this opportunity and having fun and really having a go when I get out there," he said.

"You never know what happens after that, but I'm just looking forward to taking on the opportunity."

Former Saint Clint Jones gets to know his new teammates at training. Picture: AFL Media

Essendon football operations manager Rob Kerr also confirmed on radio station 3AW that Michael's fellow ex-Lion James Polkinghorne had been elevated from the Bombers' VFL team and would also play in the NAB Challenge.

Michael and Polkinghorne join former Saint Clinton Jones, Mitch Brown (Geelong), James Magner and Mitch Clisby (Melbourne) and Jared Petrenko (Adelaide) as the club's other ex-AFL recruits for the NAB Challenge series.

Ex-Melbourne midfielder James Magner keeps a close eye on the ball at Dons training. Picture: AFL Media

Kerr said key Bombers not facing infraction notices, such as star midfielder Brendon Goddard, would not be expected to play extra minutes during the pre-season to compensate for the absence of their senior-listed teammates. 

He said they would play during the NAB Challenge, but on a restricted number of minutes to minimise the risk of injury.

"We really don't want to compromise that by playing them more than they would otherwise," Kerr said.

- with Michael Whiting