SYDNEY Swans coach John Longmire has praised dynamic youngster Isaac Heeney's start to his AFL career, but has also warned the 18 year-old to prepare for some tougher times ahead.

Heeney booted four goals – three of them in the first half – in another classy performance in the Swans' 21-point win over Greater Western Sydney at the SCG on Saturday. 

The Swans' academy product combined well up forward with Lance Franklin, who kicked five goals in another hard-working display, and Longmire says that while Heeney has stepped straight into senior football seamlessly, logic tells him it won't last forever. 

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"We know footy doesn't get easier, sometimes it can get a bit harder, but he competes every week and it gives him a real chance when he's able to do what he's able to do in our forward line," Longmire said.

"He's hard, he competes, he's composed as well, so not only was he able to hit the scoreboard tonight he was able to set a few up."

Heeney was subbed out of the match after crashing heavily into the goalpost while kicking his fourth goal in the final term, but he wasn't injured in the incident.

"It didn't look great on the vision, I didn't know someone could bend that way, but he's OK now,' Longmire said.

"We subbed him just as a precaution, we were looking to do something anyway in that last 15 minutes and because of that, our doctors suggested we do it with him.

"It was a pretty easy decision, we make sure we look after him." 

Longmire was also pleased with the performance of club great Adam Goodes, especially given the Swans' reserves suffered a heavy defeat at the hands of the Giants' second side in the NEAFL. 

"I thought he was OK, he said he felt really good being able to run out the game, got a good run and kicked three goals. He feels better for that which was what the idea of the whole thing was in the first place," Longmire said. 

The coach was positive about the champion's contribution this week, but remained coy when asked if Goodes had done enough to earn himself a recall for the Swans' round four clash with Fremantle in Perth next Saturday night. 

"We'll see," Longmire said.

Click here to watch John Longmire's full post-match media conference