FOUR crucial errors in defence were the difference between St Kilda winning and losing to Port Adelaide, according to coach Ross Lyon.

The Saints lost for just the second time this year, going down to Port Adelaide by seven points in the round seven clash at Marvel Stadium.

"It was a really high-pressure game, they applied a lot of heat. I thought the scoreboard wasn't an indicator of the first quarter, what was really going on out there. But we made them pay," Lyon said.

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"The second quarter was the reverse, we dominated entries. I thought we had some shallow entries, so I asked them to put it in (deep), and I need to be careful what I say, because they're so coachable. We didn't get bang for our buck, and they scored quite easily. 

"We're disappointed, because we thought in the end we could have won, but there's some execution – everyone wants to complicate it, but if I really simply look at it, outside their forward 50 possession gains where we turned it over and they kicked four goals, they basically almost didn't score off possession. 

"We defended the ground really well. They just got a bit of clean air, scored out of the middle and a few stoppages, but nothing dramatic. To me, we turned it over four times in our D50. If I took them out, and I think a little bit of efficiency, I'm not unhappy. A five-day break, we worked really hard, we gave ourselves an opportunity to win."

One of those four turnovers in defensive 50 came after Josh Battle was called to play on upon taking a half-step. Charlie Dixon smothered the kick, and Sam Powell-Pepper kicked the resultant goal, a crucial major in a tight game.

"I had a discussion with the umpires during the week about that stepping off the line. It didn't even look like he stepped off it. I rang Dan Richardson during the week, because there was one on Benny Paton. It's really interesting, that half a step," Lyon said.

"Not that I'm blueing, we just need some clarity, because it feels like it's been really tightened up. The rule is a bit old, you're meant to go line of goals from wherever you are on the ground, so I'd like that clarified, because that hurt us."

One aspect of the gameplan Lyon will be working on ahead of next week's clash against North Melbourne is getting bang for buck when going forward.

"I mean you can complicate it, but our efficiency all year, even though we've been scoring quite well, we might have a quarter where we're really efficient, it's been a bit of an issue," he said.

"Even though we've been in the top eight for attack, we've had lots of opportunities, but we're down at the bottom end for inside 50s, for efficiency. Ultimately, that probably hurt us overall. I thought our last quarter was really good, we fought on. But to their credit, they brought a lot of heat, they're a really good team."

Like Lyon, Port Adelaide coach Ken Hinkley made a point of emphasising the pressure both sides applied, and was thrilled to come away from Melbourne with the four points.

"I was sitting down on the beach – the beach, I wish I was at the beach, bloody hell, that would have been a bit easier – but I was on the bench and you could feel the pressure in the game, you could genuinely feel the pressure in the game," he said.

"That was a big game, I thought, and for those who watched, contested footy, two sides going really hard at it all night, our boys and the Saints boys gave four quarters of hard effort, and I thought we were lucky enough to be in front at the end."

Hinkley was pleased with the efforts of young midfielder Jason Horne-Francis, but said it was a collective effort in the middle of the ground.

"He's got a lot to work on and a lot to improve to, but I thought again tonight he showed some growth in his game and there's still further growth to come in all phases of the game," he said.

"But tonight was really impressive. You saw his power tonight, that's what we know about him and everyone knows about him in his draft year, he's got this great power.

"Jason may have been the result of some great work going on inside. But I think some of the young players on the inside – (Connor) Rozee, (Zak) Butters, Jase is in there himself, Ollie (Wines) was in there at times, Travis (Boak) went back in a fair bit more tonight than we have the past few weeks – but we felt as if we could get a bit of speed on the floor, that might be helpful against the Saints."

Hinkley was also keen to seek clarification from the umpires about the sheer number of frees the side has conceded this year.

"For us, I'm not an umpire bagger or whinger, but at the moment, we're a long way in front of the free kicks against. It'd be nice to get some clarity from the umpires back to us, if we're that poor at some of the things we're doing, I'd just love to get that direction coming back our way," Hinkley said.

"Because I don't want to go searching for it, in a two-way conversation, it'd be nice to feel why we've given away 20-plus more free kicks for holding the man in this competition, six rounds in. 

"That's a big number, a big, big number. That gives away 300-400m in a game of football. We're aware of it, we're working at it, but we seem to be keeping on doing it, so we must have something wrong with the umpiring of the game."