The Dragons trailed 4-0 after less than a minute but absorbed a mountain of pressure to hit back with tries to Paul Vaughan and Tyrell Fuimaono to lead 12-4 at the break.

It was a promising display, but it was all one-way traffic in the second as a largely second-string Rabbitohs outfit piled on 22 unanswered points.

They did it with the likes of Latrell Mitchell, Damien Cook, Adam Reynolds and Cody Walker watching on from the bench for the whole second stanza.

Tyson Frizell did the same for the Dragons, while other big guns followed as the match progressed, but McGregor admits his side was out-hustled when changes were made.

"I just thought the second half what they put on the field had more purpose behind it," McGregor said.

"There were two periods of the game, the start of the first half, and then that period in the second half where we just didn't control the ball at all for long periods of time.

"They had 20 offloads for the game, 7-1 at halftime and 13 in the second half. It just showed we didn't have control of possession and field position. Those big boys they had out there got on the front foot on us.

"If you look at the way they scored their tries they were one off the ruck with an offload and put it down. In the first half we repeatedly defended that sort of of stuff.

"We had had different players out there at that time but we'll obviously work on that because it's not what you want to see in your final trial."

It's not the ideal final outing prior to season kickoff but McGregor said it certainly served it's purpose after stronger showings at the Nines and against Newcastle a fortnight ago.

"You obviously want to win every game you play," McGregor said.

"We had a good series in the Nines and backed that up with a handy win against Newcastle. I thought the first 40 was good with the amount of work we did in defence.

"I thought we started a bit nervously and turned the ball over and they built some pressure. They had four repeat sets but, besides the first scrum, we turned them away consistently and came in [to halftime] with a nice handy lead at 12-4.

"Souths are a pretty strong physical side, their back-line's one of the better ones in the comp and we were able to defend that for long periods of time which was a positive for us.

"We got through unscathed, we gave a lot of guys opportunities, we learned a lot from both halves and settled on a line-up for round one. I certainly got some answers there tonight so we'll settle on it for a weeks' time."