PORT Adelaide's Mark Williams will coach the club for the final time against Collingwood at AAMI Stadium on Friday night, but he has signalled that he wants another senior position at AFL level.

On Thursday Williams declared his intent to see out his contract with the Power, which would have expired at the end of 2011.

However, a meeting with president Brett Duncanson set in motion a remarkable chain of events, which culminated in the club and its longest-serving coach parting ways on Friday morning.

There was speculation the Port Adelaide hierarchy had sacked the premiership coach - after seven straight losses and candid comments about his future at Alberton - but Williams denied this was the case.

"Day after day and week after week you see the press and it was getting untenable for the club," a very emotional Williams said at Friday's media conference.

"I spoke to Brett about it and you have to do the right thing by the club.

"It was going to happen at some stage. To get the first-ever gig in your AFL coaching career and last this amount of time has just been brilliant.

"I've been so lucky and Sheeds (Kevin Sheedy) is probably the only one in modern times who has done anything like it."

Williams touched on the irony of finishing his coaching career at Port Adelaide against the club he captained in the 1980s and played his last AFL game against as a Brisbane Bear.

But the timing was anything but ideal for the team, which will arrive at AAMI Stadium on Friday night not knowing who will coach them next week.

Duncanson, who maintained the club's decision to reappoint Williams last year was the right one, said the Power had little choice with the surprise timing of the announcement.

"If we tried to let Mark coach tonight and leave an announcement until Monday, then all you guys [in the media] would have been making all sorts of noises about all sorts of things," he said.

"Today isn't perfect timing, but there never is a perfect time."

Duncanson said Port Adelaide would appoint a caretaker coach for the rest of 2010, with assistants Matthew Primus and Dean Laidley the obvious candidates.

"I'm sure [football manager] Peter Rohde and Haysie (CEO Mark Haysman) will deal with that this afternoon. We'll get through tonight and then regroup tomorrow and look at those issues," he said.

Williams said rumours he would join Sheedy at Greater Western Sydney were "absolutely wrong" but that he hoped to continue coaching elsewhere.

"Sheeds and I are mates, but what happens in the future I'm not sure … it's been so long since I've had any break from anything," Williams said.

"My mate [former fitness coach] Darren Burgess is over at Liverpool now, so I might pop over there and help. Rafael Benitez isn't there anymore. [Roy] Hodgson is there, he’s a lot older than I am.

"I'm not sure what I'm going to do, but I feel like I've got a lot of energy and interest in the next challenge and the next opportunity."

A colourful character, Williams conceded he has had his share of critics from within the club's supporter base.

He couldn't resist a joke about those relationships, but assured the Port Adelaide faithful that the club was in a good position.

"I am leaving today because of illness and fatigue … the supporters have become sick and tired of me. I read that somewhere and thought I'd use it one day," Williams said.

"[But] seriously, in two or three weeks our better players will be back playing and our full list will be available and you'll see how good Port Adelaide is."