THE opening half-an-hour of Rangers' second-leg Champions League qualifier against Union Saint-Gilloise will be pivotal.
That's the view of former Celtic star Kris Commons.
Giovanni van Bronckhorst's men need to overturn a 2-0 deficit at the half-way point in the tie.
They will take on the Belgian outfit in Glasgow tomorrow night, with a spot in the Champions League play-offs on the line.
Rangers got back to winning ways at the weekend, with Alfredo Morelos making a scoring return against Kilmarnock at Ibrox.
And Commons reckons the opening stages of Tuesday's game will be key, with the onus on the home side to spook their opponents along with the packed crowd.
He wrote in his weekly Daily Mail column: "It's all about how Rangers start. The atmosphere will be electric and they have to feed off that and keep the fans with them.
"The Belgians won't have experienced anything like it. Far better teams than them have been intimidated by the atmosphere that the big clubs in Glasgow can generate on nights like these.
"If Rangers score in the first 30 minutes, I think the momentum will turn and they'll get through with something to spare. It's a matter of unsettling Union from the very first minute.
"You want to get them facing their own goal and remain under pressure. If they concede early, I could see them crumbling.
"But at the same time you don't need to be diving into silly challenges and being too aggressive.
"The last thing Giovanni van Bronckhorst needs is his side going down to ten men and that's going to make a tough task significantly harder.
"You can't win it within ten minutes but you can lose it. The energy in the ground has to inspire you. You can't get carried away.
"Celtic faced exactly the same scenario when we faced Shakhter Karagandy in 2013 and succeeded in coming back from two goals down. We did that by staying ice cool."
On Morelos, Commons added: "With the stadium packed to the rafters, they will back themselves to turn the tie on its head. No player has scored more goals in Europe for Rangers than Alfredo Morelos.
"After so long out, it's going to take him a few matches to get fully up to speed but his mere presence tomorrow is a huge boost.
"It's not just his goal record. His physicality poses different problems to their defenders. He's a handful. He'll wind them up and push them about. They won't be looking forward to facing him."
