An exhilarating game at Ibrox saw Rangers beat Red Star Belgrade 3-0 in the first leg of their Europa League round-of-16 tie on Thursday.
A contest dominated by early VAR decisions saw goals from James Tavernier, Alfredo Morelos and Leon Balogun secure a big win for Giovanni van Bronckhorst's men.
The visitors conceded twice, had two goals ruled out for offside, and saw a penalty saved by Allan McGregor in a frenetic opening 25 minutes in Glasgow.
Dejan Stankovic's side will still believe they can turn things around at the Rajko Mitic Stadium next week, where they have won three of their four Europa League home games this season (L1), but only once have they won by more than one goal (4-0 v CFR Cluj).
Red Star made a bright start and Aleksandar Katai had an early goal disallowed for offside, but it was Rangers who took the lead on 10 minutes when a VAR review judged that Ryan Kent had been tripped in the box by Slavoljub Srnic, with Tavernier dispatching the penalty into the top-right corner of the net, despite slipping over.
Everything was going wrong for the visitors as they had a second goal ruled out for offside, before a cross from Ryan Jack off a short corner dropped to Morelos, who fired past Milan Borjan to double the lead for the Scottish champions.
A remarkable opening period continued as Red Star were awarded a penalty on 23 minutes after Jack fouled Guelor Kanga in the box, but McGregor got a strong right hand to Katai's spot kick to keep it out.
Glen Kamara almost made it three before half-time after good work from Calvin Bassey and Kent down the left, but the Finland midfielder lifted his effort just over the bar, though it was three six minutes after the break as Balogun rose highest to plant a header past Borjan from an out-swinging Tavernier corner.
Kanga crashed a shot against the crossbar and substitute El Fardou Ben Nabouhane had a third goal ruled out for offside as Red Star looked for a way back in, while Connor Goldson missed a glorious chance at a fourth at the back post off a Tavernier free-kick, but Rangers will be happy with another impressive win in Europe.
What does it mean? VAR to the rescue for Rangers
It was an electric start at Ibrox, but the busiest man involved in the game was the video assistant referee who was forced to make three huge calls in the first few minutes, all of which went to Rangers (correctly, it must be said).
Two disallowed goals for the visitors either side of a penalty award to Van Bronckhorst's men swung the tie in their favour early on.
Rangers rode their luck at times but also showed that their shock elimination of Borussia Dortmund in the last round was no fluke as they ensured a good first-leg lead as they look to progress to the quarter-finals for the first time since their run to the final in 2007-08.
Morelos makes history
The Colombian striker is somewhat of an enigma, but usually turns up when his team needs him, especially on big European nights.
Morelos has now scored seven goals in Europe for Rangers this season – surpassing James Forrest in 1964-65 as the player with the outright most goals in a single season in major European competition for the club (excluding qualifiers).
Serbians' struggle in Scotland
Former Inter midfielder Stankovic will have been pleased with the effort from his team and bemused as to how they were 2-0 down at half-time, but they have a lot to do next week in the return leg.
Red Star have now won just one of their previous seven matches away to Scottish opponents in European competition, with that victory coming in their first such match back in November 1961 against Hibernian in the Fairs Cup.
Before the return leg in Serbia next Thursday, Rangers travel to Dundee in the Scottish Cup quarter-final on Sunday while Red Star are away to Metalac GM in the Serbian SuperLiga on Monday.