The Queensland Reds have rounded out their most successful Super Rugby season in five years with a 48-27 victory over the Sunwolves.

But for the second week in a row, the Sunwolves were forced to play out more than half the match with only 14 men after a contentious red card to Ed Quirk.

It robbed them of any chance they might have had, with the Japanese outfit eventually succumbing to a seven-tries-to-three defeat on Friday night at Suncorp Stadium.

Flanker Quirk was sent off in the 37th minute for what referee Ben O'Keeffe and television match official Damien Mitchelmore deemed to be foul play on Hamish Stewart.

Replays showed Quirk, a former Reds player, made contact to Stewart's face with a closed fist while both were on the ground -- but the force with which it was delivered was so light to be almost negligible.

Players on both sides were in disbelief when O'Keeffe eventually produced the card after a lengthy stoppage.

Reds coach Brad Thorn said it ruined the game.

"For me, a red card has to be massive to send someone off," Thorn said.

"A horrendous spear tackle, kicking someone on the ground, eye gouging, not love taps ... but then maybe I'm an old relic."

Sunwolves coach Tony Brown described the decision as an embarrassment to the sport and saying referees were trying to "promote themselves" by making controversial calls.

"Every rugby player who's ever played the game is looking at that and saying it's not a red card," Brown said.

"I think I'm with Michael Cheika, we need the referee in here answering these questions because he's the only one in the world who thought that."

The Reds were up 22-13 at the time and missing one of their own, with Duncan Paia'aua still in the sin bin after conceding a penalty try for his deliberate knockdown in the 28th minute.

They copped another yellow five minutes into the second half when Caleb Timu shoulder-charged a prone Hayden Parker in the head -- a dangerous offence for which a red was much more deserving.

The card controversies and the shoulder injury that ended skipper Scott Higginbotham's night just before halftime took some of the gloss off an otherwise solid night at the office for Queensland.

It was the Reds' second win in a row and sixth for the season, ensuring their best return since 2013, the year they last made the Super Rugby finals.