Rangers' sensational win over Borussia Dortmund brought a further boost to the Scottish coefficient - and they can all-but secure a top 10 place against Red Star.
Gio van Bronckhorst's side are the only Premiership team left in Europe after they came through their Europa League playoff with a 4-2 win in Germany and a 2-2 draw at Ibrox.
With UEFA awarding two points for a win and one for a draw, divided among the number of teams that entered European competition, that added 0.6 to the Scottish coefficient.
Rangers were also given a bonus point for reaching the last 16, which with five teams in Europe adds a further 0.2 to the Premiership coefficient.
They've been drawn against Red Star in the next round and that could be a shoot-out for a crucial place in the top 10.
This season's league winners are very likely to go straight into the group stage of the Champions League, but a place isn't guaranteed.
Scotland started the season in 11th position, with 26 teams guaranteed to be in the groups for 2022-23.
Those are the top four from the English Premier League, La Liga, the Bundesliga and Serie A, the top two from France and Portugal, plus the champions of Russia, Austria, Belgium and the Netherlands.
A further two places are reserved for the winners of the Champions League and Europa League but if the former have already qualified via their domestic league their place goes to the nation ranked 11th.
Not since Chelsea in 2012 has the winner of the competition failed to qualify, so there's a very good chance of Celtic or Rangers going straight into the group - but if Scotland ends the season the top 10 it will be a cast-iron guarantee for next season's champions and the nation is currently ranked ninth.
Only Serbia can realistically deny the Premiership that top 10 place, making Rangers' clash with Red Star all the more important.
The balkan state closed the gap over the last round of fixtures, with Partizan Belgrade winning both legs of their tie with Sparta Prague.
Since Serbia only entered four teams into Europe this season that added a point to their coefficient to leave them on 32.875.
The Premiership is a shade over two points ahead at 2.025 but, crucially, both Red Star and Partizan are still playing in Europe and able to pick up points.
The latter have a tough tie against Feyenoord in the Europa Conference League but, remember, any win for them is worth more than for a Scottish team as it's divided by four rather than five.
That means even if Partizan win one leg and lose the other they'd add 0.5 points to the Serbian coefficient.
In that context it becomes clear how crucial Rangers clash with Red Star is, with another bonus point on offer for reaching the quarter-finals.
If we take the worst case scenario for the Scottish coefficient that sees the Premiership champions lose both games, that by itself would add 1.25 to the Serbian coefficient (four points for two wins, plus a bonus point, divided by four).
Should Partizan win even one of their games against Feyenoord the point gap would shrink to 0.275 with Red Star just one win away from guaranteeing that Serbia finishes ahead of Scotland.
That wouldn't necessarily rule out a top 10 place for the Premiership but in that scenario all eyes would be on Russia.
Their top flight is currently in 10th place, sandwiched between Scotland and Serbia, and Spartak Moscow are the only Russian side still in Europe.
They face RB Leipzig in the last 16 and, having entered five teams, every win is worth the same as a win for a Scottish side.
The Russian top flight is currently 0.418 points behind the Premiership, meaning one win isn't quite enough to overtake.
But Spartak would also earn a bonus point for qualification to the quarter-finals to add a further 0.2 to the Russian coefficient - a problem if Rangers go out.
It all adds extra incentive for Van Bronckhorst's men, who can basically guarantee a top 10 place and the resulting Champions League place by knocking out Red Star.
