Sydney has to address its players' failure to adapt to this season's stricter holding the ball interpretation, coach John Longmire says.

The Swans lost the free kick count 18-31 in their 23-point loss to the Western Bulldogs at Etihad Stadium on Friday night.

Longmire said the difference in the way both teams had coped with the prior opportunity rule had been glaring.

"I've just got to look at the way we coach them to be honest. The holding the ball decision was us and them," Longmire said.

"We must have missed something. We need to have a look at that, about what the prior opportunity (rule) is and how we're doing it versus our opposition.

"So we need to look into that, clearly, because it just felt at the time what we were doing around the contest compared with the opposition - they must be doing something a bit different we need to look at.

"We're clearly doing it the wrong way, so we need to sharpen up on that."

The Swans unveiled three debutants against the Bulldogs: Will Hayward, Robbie Fox and Nic Newman.

All three showed extremely promising signs in the high-pressure contest.

Hayward and Newman both finished with 16 possessions and six tackles, while Newman also coolly converted a 40m set shot late in the second term that briefly put Sydney back in front.

Fox had 13 possessions and three tackles, while second-gamer Oliver Florent also had 13 possessions and kicked a goal after a brilliant run-down tackle on Bulldogs speedster Jason Johannisen in the second quarter.

Longmire was delighted with the youngsters' performances.

"We had a really young team in tonight, so the way they went about it for the majority of the game I was really happy with," Longmire said.

"And to fight back, and obviously to lose Kurt (Tippett) in the first quarter, but then to keep going as long and as hard as what we did in that last term and, having young kids in their first games play 105-110 minutes, I thought the intensity and effort was pretty good.

"Some of the kids I thought were just fantastic. I mean that's pretty red-hot footy – it doesn't get much hotter than that out there against last year's premiers, Friday night footy – and to have some of the efforts from the younger boys was just really good to see.

"Our effort and intensity around the ball was fantastic, the ability to be able to come back and hit the front was fantastic, but you don't get any points for it and that's the reality of it."