But then the side lost Reweti to injury while Matapuku also hurt his shoulder, and when another player went down, the Mustangs bench was empty.
"[Northland] fought their way back," said Reweti.
"They had a pretty good squad too, a couple of nifty wingers.
"The guys had to play a gutsy last 30 minutes with no subs.
"They scored their last try right at the end."
Northland rotated their interchange well to keep fresh legs on the paddock and ran through to get repeated tries, including a converted try at the finish.
The Mustangs will now take a bye weekend, and other than Matapuku, most of the other niggling injuries should be alright by the time the side travels to play the Taranaki Sharks in New Plymouth on September 14.
The Sharks were in a similar predicament to the Mustangs, as without a club league season, most of their players stayed fit by going to their local rugby union clubs.
"I think it's going to be a tough game, it's hard when we play Taranaki," said Reweti.
"They always turn it on, especially up there."
Last season, the Mustangs defeated the Sharks 30-26 in Oakura, after the players from both teams had been involved in the same TRL club competition earlier in the year.