Another VAR call by referee Artur Dias then saw City awarded a 24th minute penalty – only for Mahrez’s subsequent spot-kick to be saved.
And the TV monitor again took centre stage on 30 minutes when Sergio Gomez was shown a straight red card for a late challenge on Copenhagen’s Hákon Haraldsson after referee Dias was again advised to refer to the VAR monitor.
Despite being a man down though, City looked the more likely to score but ultimately settled for a goalless draw at the Parken Stadium.
And our qualification for the knockout stages was then confirmed later on Tuesday when Sevilla could only draw 1-1 at Borussia Dortmund.
In front of a packed and partisan home crowd in the Danish capital, Pep Guardiola’s side were looking to make it four wins out of four in Group G.
The City boss had opted to ring the changes with Erling Haaland one of five players to move to the bench from the side that had beaten Southampton at the weekend with Julian Alvarez leading the forward line.
And within six minutes the Argentine almost made an instant impact.
A City counter-attack sparked by a Jack Grealish surge up the left flank put in Alvarez on the overlap and only a faint touch by Copenhagen keeper Kamil Grabara denied the Argentine a fifth goal in City colours.
VAR then took centre stage in what was to prove an incident-packed opening 45 minutes.
City then looked like we had made the breakthrough on 10 minutes when Rodrigo thundered home a spectacular 25-yard right-footed drive from the edge of the box that flew into the top corner of the net.
However, after a lengthy VAR check, referee Artur Dias from Portugal opted to chalk off the effort due to a handball offence against Mahrez – much to City’s frustration.
It wasn’t all one-way traffic and Ederson needed to be alert to tip over a dipping effort from Lukas Lerager as the hosts reminded everyone of their quality.
VAR was then to play a decisive role once more on 24 minutes as City were awarded a penalty.
Copenhagen defender Nicolai Boilesen was adjudged to have handled the ball via another VAR check after a City cross arced into the Copenhagen box and struck his outstretched arm.
Mahrez stepped up to take the spot- kick but Copenhagen keeper Grabara proved equal to the task, the Polish international diving to his right to palm the Algerian’s left-foot effort away.
And VAR was centre stage once again on the half hour when Sergio Gomez was sent off for a foul on Hákon Haraldsson as the pair tangled on the periphery of the City box.
Once again, referee Dias was instructed to look at his pitch side monitor and the Portuguese official then showed our Spanish defender a straight red card with Copenhagen skipper Viktor Claesson hitting the resulting free-kick straight into the City wall.
Guardiola responded to City going down to 10 men by bringing on Ruben Dias from the bench in place of Mahrez to shore up our back-line with our rear-guard having to be alert and disciplined in the face of a rejuvenated Copenhagen.
De Bruyne twice threatened early after the restart as City sought yto conjure up the all-important breakthrough.
With time slipping away Grabara denied City again, palming away a low Cancelo drive before an Alvarez header also flashed just over the bar with Gundogan also seeing an injury time shot saved as City settled for another important point.
Manuel Akanji again produced another assured and composed display in City’s defence.
Having started at centre back, the Swiss international was then redeployed to right back after City had gone down to 10-men.
In all of his work, Akanji was a model of calm, cool consistency and ensured that City took the sting out of the hosts’ best efforts up front in what was a partisan atmosphere.
Remarkably, Riyad Mahrez’s missed penalty made it 24 spot-kicks missed in all competitions during Pep’s time in charge at the Club to date.
Hopefully, Tuesday night’s miss will get our bad luck out of the way as regards spot-kicks for the remainder of the season!
FC COPENHAGEN: Grabara, Khocholava, Claesson (c), Lerager, Daramy, Jelert, Boilesen, Lund, Haraldsson (Johanneson 59), Kristiansen, Stamenic.
Subs: Johnsson, Ryan, Diks, Sorensen, Mukairu, Ankersen, Clem, Roony
CITY XI: Ederson, Cancelo, Akanji, Laporte (Ake 87), Gomez, Rodrigo, Gundogan (c), De Bruyne (Bernardo 77), Mahrez (Dias 33), Grealish (Foden 77), Alvarez
Subs: Ortega Moreno, Carson, Haaland, Palmer, Lewis, Wilson-Esbrand
What it means
The draw took City to 10 points from four games – and with Sevilla later failing to win at Borussia Dortmund on Tuesday our place in the last 16 is now confirmed, meaning we are the first team to qualify.
"Really satisfied, with the team that gives everything, 10 v 11 in Europe, the physicality of them, we concede few (chances), we start really well, many things happen.
"Mathematically we are not in the next round - we are not there, but we are almost there. We have to lose 5-0 to Sevilla at home.
"We are going to recover, prepare for the next games, go to Dortmund and try to get results, and Sevilla, to finish first in the group stage."
City face a huge Premier League assignment on Sunday when we travel to take on Liverpool for one of the most eagerly-awaited matches of the season.
Kick-off at Anfield is set for 16.30pm (UK time) and we will have our usual comprehensive coverage across the official Man City app and website.
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