Lowrie injured his ribs against Penrith on May 18 and, while it was predicted he would miss two to three games, he had been keen to return for last Sundays home encounter with Newcastle.
Ultimately he missed that match, though, and is out again for the Vodafone Warriors clash against Brisbane at Suncorp Stadium tomorrow night.
Ropati is still being troubled by a hamstring strain and, despite being named recently for the Vulcans, he hadnt recovered fully to make a return. He remains a week to week proposition.
Giant forward Sam Lousi was originally named to make his comeback from a long-term foot injury with the Vulcans in their New South Wales Cup clash against Illawarra yesterday. However, he was subsequently ruled out.
Also close to a return is utility Sio Siua Taukeiaho, who has been recovering from a broken leg, while fellow utility Carlos Tuimavave is still troubled by a neck injury which prevented him returning for the second half of last Sundays 28-12 victory against Newcastle.
The full injury list for the NRL squad is:
Todd Lowrie - Loose Forward - Ribs (Round 13)
Jerome Ropati - Centre - Hamstring (Round 13)
Sam Lousi - Prop - Foot (Round 13)
Carlos Tuimavave - Utility - Neck (Round 13)
Sio Siua Taukeiaho - Utility - Leg (Round 14)
Sione Lousi - Prop/Second Row - Knee (Season)
Steve Rapira - Prop/Second Row - Knee (Season)
Ben Henry - Second Row/Centre - Knee (Season)