Cardiff are awarded a penalty and go to the corner.

The rolling maul doesn't really get going, they lose the ball in contact and Brandon Thomson is able to hoof way downfield.

It's a very windy day in Glasgow as Warriors full-back Stuart Hogg has just found out.

He looks to kick downfield from inside his own 22 but his kick is caught by the wind and incredibly bounces dead behind the Cardiff dead-ball line.

Scrum Cardiff.

Cardiff fly-half Steve Shingler gets us under way at Scotstoun.

With only three of the group runners-up making it through to the quarter-finals along with the five group winners, Glasgow head coach Dave Rennie is in no doubt they need a bonus-point victory.

"It's a big game. We need four tries today because it's a real massive group of teams in at about 18, 19, 20 [points]," Rennie said on BBC Radio Scotland.

"It doesn't mean that we play hectic. We want to exert pressure, you may see us early if there's a chance to go for the posts, going for the corner."

On dropping Adam Hastings for Brandon Thomson at fly-half, Rennie says: "Obviously some of his distribution has either been intercepted or called forward for tries. And maybe some of his kicking options haven't been great. He's working really hard on that during the training week but we haven't seen evidence of that on game day, but I've no doubt he'll turn it around."

Image source, SNS

Perhaps Dave Rennie's biggest call in this weekend's team selection is the decision to bench fly-half Adam Hastings - who has endured a tough few weeks - in favour of Brandon Thomson.

But his team-mate Fraser Brown, part of our Radio Scotland commentary team today, has no doubt the young Scotland international will bounce back.

"A lot of the pressure falls on his shoulders," Brown said.

"Adam will be ok, he's very talented and sure of himself in a good way. He's been working very hard on the things that haven't been going too well in the last couple of weeks."

Tom English
BBC Scotland's chief sports writer

A must-win game for Glasgow - and probably a must-get bonus point as well. Things are incredibly tight in these groups and a point here or there could make all the difference in determining the last eight. I reckon a five-point win for Glasgow today will be enough to get them into the quarter-finals as eighth seed. To do that they need to look after the ball and control the tempo. They like to play with risk but some of the stuff they have delivered recently has strayed over the line from a gamble to a gullibility. Street-wise, attritional, controlled rugby should get the job done.

Cardiff's season has seen their form fluctuate up to this point.

They sit fifth in Pro14 Conference A - which also features Glasgow - with six wins from their 13 matches.

Their Champions Cup campaign started promisingly with a victory away to Lyon in France, but Glasgow's bonus-point win at the Arms Park in October derailed their challenge and, having failed to take anything from back-to-back meetings with Saracens, the Blues are now out of the running for the last eight.

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Glasgow go into this match in wretched form having lost their last three matches.

They were overpowered home and away by rivals Edinburgh in the 1872 Cup double-header and fell to a dispiriting loss to Benetton in Italy last weekend.

"Obviously the last three weeks have been disappointing, but we've created a lot of opportunities in those games and just haven't been as clinical as we've needed to be," said head coach Dave Rennie.

Read more.

Image source, BBC Sport

Peter Wright
Former Scotland prop on BBC Radio Scotland

Full-back Stuart Hogg is fit to return for Glasgow among 11 changes to their side for Sunday's pivotal Champions Cup pool match against Cardiff Blues.

Wing Tommy Seymour is also back while Brandon Thomson starts at fly-half, with Adam Hastings on the bench.

Wing Tom James returns for Blues for the first time in over a year after time out to deal with depression.

Former Wales and British and Irish Lions hooker Matthew Rees is also back after recovering from a knee injury.

TEAMS

Glasgow Warriors: S Hogg, T Seymour, N Grigg, S Johnson, DTH van der Merwe; B Thomson, A Price; O Kebble, G Stewart, D Rae, R Harley, S Cummings, R Wilson, C Gibbins, M Fagerson.

Replacements:K Bryce, A Allan, P Du Plessis, T Swinson, C Fusaro, G Horne, A Hastings, L Jones.

Cardiff Blues: D Fish; O Lane, H Millard, W Halaholo, T James; S Shingler, L Williams; B Thyer, M Rees (capt), D Lewis, G Earle, R Thornton, S Lewis-Hughes, J Navidi, S Davies.

Replacements:E Lewis, R Carre, S Andrews, M Cook, N Williams, T Williams, J Evans, A Summerhill.

Referee: JP Doyle (England)

Image source, SNS

Saracens should take care of bottom dogs Lyon in France today to seal qualification to the quarter-finals, and top spot in Pool 5 if Glasgow don't beat Cardiff.

That match also kicks off at 15:15 so we'll know a lot more at full-time today.

Image source, BBC Sport

It's already been another wonderful weekend of Champions Cup rugby and today's action will bring further clarity as to which teams will reach the quarter-finals.

Glasgow can get to 19 points with a bonus-point victory over Cardiff at Scotstoun this afternoon and that tally normally ensures a last eight spot.

However, the way the other pools are shaping up, they could still require another point away to Saracens - who should seal qualification today with victory over Lyon - on the final day.

A win without a bonus point would almost certainly leave them with work to do, and defeat would leave them staring down the barrel of elimination.

Image source, Getty Images