World Cup - Mitchell injury mars easy Australia win
Two-times champions Australia, who have only once before failed to qualify top of their pool, lead the group with 15 points ahead of Ireland, 13 and Italy on 10 ahead of their Dunedin showdown.
Australia's bonus-point victory was always going to be a formality but, having been forced to start with loose forward Radike Samo on the wing, Mitchell's hamstring problem is the last thing the Tri-Nations champions would have wanted.
They will be pleased with the sharpness shown in the first half as Berrick Barnes and Quade Cooper cut holes in some admittedly feeble defence to send their runners away while James O'Connor converted nine of the 10 tries.
After turning round 47-5 ahead, Australia lost momentum, and as rain made conditions difficult, Russia fought back with spirit to end their World Cup debut on a positive note.
"Overall, we're happy to get the win but at the back end there things didn't really go the way we wanted," Australia captain James Horwill told reporters.
"We did what we needed to do and now we move on and just wait to see who we play next week."
The Wallabies hit the ground running and scored some lovely tries during 40 minutes of virtual one-way traffic.
Impressive flanker David Pocock scored two while hooker Stephen Moore finished off a cracker after a wonderfully visionary pass by Mitchell.
Mitchell added his second try after the break but then pulled up when going for what would have been his third and coach Robbie Deans said later that the injury "looks a bad one" for the winger, who suffered a horrific broken leg in April.
"It doesn't look good. It looks like it will end his tournament," Deans lamented.
"Drew is bitterly disappointed, the whole team is disappointed for him," Horwill added.
Barnes, who had a lively game starting at inside centre, ensured Australia finished on top when he intercepted to score his second try in the final minutes.
That was hard on Russia, who could barely make a tackle in the first half but were a different side after the break.
They dominated for long spells, played some creative rugby and ended the day with three tries by Vladamir Ostroushko, Denis Simplikevich and Konstantin Rachkova.
"It was amazing, we didn't get the best of starts and we struggled to keep our composure initially," Russia fullback Vasily Artemyev said.
"In the second half we had nothing to lose so we really tried to hold onto the ball and use our backs and score a few tries.
"We put a few things right and I think we deserved our tries."
7' Barnes try - Australia 5-0
9' Mitchell try - Australia 10-0
10' O'Connor conversion - Australia 12-0
12' McCalman try - Australia 17-0
13' O'Connor conversion - Australia 19-0
16' Pocock try - Australia 24-0
16' O'Connor conversion - Australia 26-0
22' Pocock try - Australia 31-0
23' O'Connor conversion - Australia 33-0
33' Ostroushkov try - Australia 33-5
36' Moore try - Australia 38-5
37' O'Connor conversion - Australia 40-5
39' Ashley-Cooper try - Australia 45-5
40' O'Connor conversion - Australia 47-5
44' Ma'afu try - Australia 52-5
45' O'Connor conversion - Australia 54-5
47' Rachkov drop goal - Australia 54-8
50' Mitchell try - Australia 59-8
50' O'Connor conversion - Australia 61-8
60' Simplikevich try - Australia 61-13
61' Rachkov conversion - Australia 61-15
68' Rachkov try - Australia 61-20
69' Rachkov conversion - Australia 61-22
79' Barnes try - Australia 66-22
79' Barnes conversion - Australia 68-22