Essendon's batch of more than 20 top-up players will start arriving at the club next week, with the Bombers on the hunt for mature bodies to play in the NAB Challenge.

The Bombers had already drawn up a list of "preferred targets" in state leagues across the country, but begun contacting clubs and player agents on Friday after a resolution was reached for the club play in the pre-season competition.

The 25 players who were listed in 2012 and remain at the Bombers will sit out the NAB Challenge to protect the anonymity of the approximately 18 who have been provisionally suspended by ASADA.

It has left the Bombers likely to require more than 20 players to fill in across the three games, with list manager Adrian Dodoro charged with finding the extra recruits.

"We thought it was important from the point of view of our own players that we hold off on making contact with any alternatives until we were clear on what the position was going to be. Now Adrian is starting to make contact," Rob Kerr, Essendon's football manager, told AFL.com.au.

"By our estimations there's maybe eight VFL players from Essendon who we'd be comfortable would be capable of stepping up.

"We're pretty mindful that we don't want to throw anyone in for something they're not ready for. [We've] got a preference for mature bodies."

Kerr said a number of issues would now need to be addressed ahead of the Bombers' opening game against St Kilda on March 7 at Morwell, including organising accommodation, food and club apparel, as well as processing short-term contracts through the AFL.

"We've basically got two sets of players to prepare now," Kerr said.

The club estimates its access to Essendon-listed players will not exceed the low-teens for each of the NAB Challenge games, meaning another training program will also be devised for the players unavailable for the matches.

"We'll probably have separate training groups. It's a real priority that the program for our AFL-listed players doesn't change, so they need all the resources they would normally get," he said.

"More than likely we'll have an expanded VFL training session with additional resources and a really strong emphasis on improving the quality of those sessions."

After weeks of discussions about their plans for the NAB Challenge, which have ramped up in recent days, Kerr said the Essendon players were supportive of the final decision.

"I think they've got to the point where they're comfortable with it. They understand the club has a commitment to play, and I think they understand there's a whole lot of stakeholders involved in it," he said.

"It's not ideal, but I think they take assurance out of the fact that we've said to them that one thing we don't want to do is compromise how they're prepared for round one and that they've got our absolute commitment to do the best we can in that area."

After playing St Kilda, Essendon will meet Greater Western Sydney on March 13 and Melbourne on March 20.