Queensland centre Hunter Paisami has been banned for three weeks for a dangerous tackle during the Reds' season-opening win against Moana Pasifika over the weekend, while fullback Jock Campbell may also spend time on the sidelines injured.
Wallabies midfielder Paisami was given a red card for high contact on Lalomilo Lalomilo as the opposing number 12 dived towards the Reds' try-line in the first half of the 56-36 win at Lang Park.
A judiciary panel upheld the red card and banned him for matches against Western Force, Crusaders and New South Wales Waratahs, governing body Sanzaar said on Tuesday.
Paisami can return a week earlier for the Waratahs match if he participates in World Rugby's tackle education programme, Sanzaar added.
Reds coach Les Kiss said Paisami's suspension was a blow for his team and they had considered fighting the charge because they thought the tackle was fair.
"Time pressures just get on top of you. We probably didn't want to take the risk and go further with it," he told reporters on Tuesday.
With centre Isaac Henry sidelined due to a knee problem, Kiss said the Reds would consider shifting one of their wingers, Filipo Daugunu or Lachie Anderson, into the midfield for Saturday's away match against Western Force or give academy graduate Dre Pakeho a first run in Super Rugby.
Four-test fullback Campbell is also expected to spend time out of the game after suffering an injury in his right wrist/forearm region and Kiss said he was waiting on a specialist to report on the injury.
The coach also confirmed reports that injured Wallabies lock Lukhan Salakaia-Loto was close to re-signing his contract with the Reds and with Rugby Australia.