When a drawn-out stoppage-time VAR decision eventually confirmed that Riyad Marhez was onside in the lead-up to his second goal of the game, the Manchester derby's scoreline took on a complexion more representative of the balance of play at the Etihad on Sunday afternoon.
A bold first-half display from visitors Manchester United - which saw Jadon Sancho curl home a delicious equaliser either side of close-range Kevin De Bruyne strikes - soon faded in the second period and Manchester City asserted their utter dominance.
Mahrez scored to make in 3-1 in the 68th minute, a stunning half-volley from a De Bruyne corner that took a decisive deflection en route to beating David de Gea, before racing free to blast home the game's final goal late on.
In the end, it was a comprehensive performance from Pep Guardiola's champions, as City enjoyed a 69 per cent share of possession and outshot United by 24 attempts to five.
And it was a display that was all the more impressive due to the fact Liverpool had cranked up the pressure on City on Saturday.
The Reds saw off West Ham at Anfield thanks to a first-half Sadio Mane goal, the Senegalese's 12th Premier League strike of the campaign, leaving Jurgen Klopp's side just three points behind City at the full-time whistle.
City's mauling of United has restored Guardiola's side's six-point advantage at the top of the table, although Liverpool have a game in hand.
The reigning champions can be backed at 1.3130/100 on the Betfair Exchange in the Premier League Winner market. Liverpool, their last remaining realistic challengers, are available at 4.1.
The fight for fourth
United's loss to their bitter rivals dealt a concussive blow to their hopes of claiming the final Champions League-qualification berth this season, with the Red Devils now fifth.
Ralf Rangnick's men might only be one point behind fourth-placed Arsenal, but the Gunners have played three fewer games.
United are available at 4.84/1 on the Exchange in the Top 4 Finish market.
Arsenal were made to work for their coveted fourth spot in Sunday's first fixture. They travelled to Vicarage Road to take on relegation-battling Watford and escaped with all three points via a 3-2 victory.
Martin Odegaard, Bukayo Saka and Gabriel Martinelli gave the away side what looked like an unassailable 3-1 lead before the hour mark. But Roy Hodgson's Hornets fought on. Moussa Sissoko pulled back a goal for Watford, but the former Tottenham midfielder's strike arrived with just three minutes remaining and Arsenal held on.
Mikel Arteta's side are now available to back at 1.68/13 on the Betfair Exchange to finish inside the Premier League's top four places this season.
Wolverhampton Wanderers had emerged as unlikely top-four candidates after a run of six league wins from eight matches. But they lost for the third game in a row on Saturday, beaten 2-0 at home by Crystal Palace. Wolves are now eighth in the table and out to 5049/1 on the Exchange in the Top 4 Finish market.
Watford's loss to Arsenal meant they were unable to take advantage of the fact 18th-placed Burnley were hammered 4-0 by Chelsea on Saturday. The Hornets remain second from bottom and are 1.182/11 on the Exchange in the Relegation market.
A change of manager was unable to muster a change of fortune for Leeds United on Saturday. In Jesse Marsch's first game in change since replacing Marcelo Bielsa, the struggling Yorkshire side were beaten 1-0 by Leicester City at the King Power Stadium, going down to a second-half Harvey Barnes goal.
That's five defeats in a row for Leeds, who find themselves in 16th place, just two points ahead of Burnley in the final drop position having played one game more than Sean Dyche's side. They can be backed at 2.982/1 on the Exchange to be relegated this term.
Moving on a steep upward trajectory, Newcastle United continue to soar clear of the drop zone. Early goals from Ryan Fraser and Fabian Schar gave Eddie Howe's men a 2-1 victory over Brighton at St James' Park on Saturday. They are now up to 14th and out to 1716/1 in the Betfair Exchange's Relegation market.
Brentford also earned themselves some breathing space this weekend, hammering bottom-placed Norwich City 3-1 at Carrow Road thanks to an Ivan Toney hat-trick. The Bees are priced at 5.14/1 on the Exchange for a return to the second tier in 2022.