Geelong Cats players walk off the ground during the round 22 AFL match between the Geelong Cats and the Sydney Swans at Simonds Stadium on August 4, 2017 in Geelong, Australia.

Legendary journalist Mike Sheahan believes both Geelong and Port Adelaide won't have an influence this September after poor performances in round 20.

The Cats were outplayed by Sydney at Simonds Stadium on Friday night and were beaten by 46 points, while the Power were smashed in the Showdown on Sunday to the tune of 84 points.

Geelong also suffered a huge injury setback, with captain Joel Selwood now in doubt for the finals and will go in for surgery on Monday after suffering a ankle injury against the Swans.

“On what we saw at the weekend neither Geelong or Port Adelaide can have any influence in September – that’s my view,” Sheahan told SEN Breakfast on Monday morning.

“Chris Scott would have said to them about everyone says you’re a two man team, this is the chance to play a good team and show that we’re genuine, and they weren’t. They were never in the game.”

Geelong gave up their highest first quarter score at home since 1986, with the Swans racing out to a 47-15 lead by the first break.

Despite playing six first-year players, Sheahan said it wasn't the Cats' bottom tier players who let them down, but said the veterans didn't perform to their best.

“I lay the blame at the senior blokes, even Joel Selwood had one of those games where he wasn’t sure like he normally is, and then he got injured,” Sheahan said.

“I seriously think the senior blokes at Geelong were exposed again for the lack of class when Dangerfield is taken out of the group.

“How was Harry Taylor the other night? Harry’s got no stronger admirer than me over the last ten years. How was he?

“There was one bloke who wore the blue and white hoops on Friday night who was every good and earnt his keep, and that was Tommy Lonergan.”

Geelong's top four chances are now in doubt, even if they have a six-point lead over Port Adelaide, Sydney and the Western Bulldogs.

The Cats host fellow top four sides in Richmond and GWS at Simonds Stadium over the next three weeks, and also have a match at the MCG against Collingwood in round 22.