Matthew Clarke says Adelaide's midfield depth will stretch Port Adelaide in Showdown 20 at AAMI Stadium on Saturday night.

"It's going to be an interesting game," Clarke said. "Their form on the even games is really good this year. Rounds two and four (against Sydney and St Kilda) they've been unbeatable, so we've got them on (round) six, which is a bit of a problem.

"But I think probably our midfield depth would test them. Obviously we've got a few injuries in our forward half at the moment, so we've got some issues there."

Asked about the ruck duels, given that Port's promising Fabian Deluca, 19 and 203 centimetres, would be playing only his second AFL match as support for Brendon Lade, Clarke said: "Yeah, he's been playing probably career-best footy, Brendon, so hopefully he's a bit tuckered out from his efforts over the first five weeks, and we'll have an easier one this week, but I don't imagine so."

Clarke said he would be 'surprised' if key defenders Ben Rutten and Ken McGregor both started as forwards as they did last Saturday because of the Western Bulldogs' small forward lines.

Clarke, 32, will play his 236th AFL match on Saturday night, and this is expected to be the last of his 14 seasons - seven each with the Brisbane Lions and the Crows.

Adelaide has three talented young giants developing in the wings - Ivan Maric, 20 and 198cm, John Meesen, nearly 20 and 200cm, and Jonathon Griffin, 20 and 202cm.

Clarke described their progress as 'excellent' and added: "They're coming on really well. It's really positive for the club."

Asked whether he felt any additional pressure because of the big wraps about Maric, who has been in fine form with Port Adelaide Magpies in the SANFL, Clarke said: "I feel pressure to perform every week. But those guys will develop and fortunately it's not my decision who gets a game, so I don't have to worry too much about it. I've just got to get out there and get a kick.

"The body feels pretty good. I had a slight niggle last week but it came up. Before that it had been really good so I can't complain."

When Clarke said he was 'always enthusiastic', it was put to him that he might be able to play on for one or two more years, and he smiled and replied facetiously: "Three or four, I'd imagine. I'm travelling pretty well and the club's really happy with my form, so they'll be looking to sign me up on a long-term deal, I'd imagine."

Ben Hart (tonsilitis) did not train at AAMI Stadium on Wednesday but was not considered to be in doubt for Saturday night's match, and Simon Goodwin was told to rest because of his recent workload and outstanding form.

Mark Ricciuto (hamstring) and Scott Thompson (groin) trained earlier in the day. They are expected to be named in the 25 and have fitness tests on Friday.