Late goals from Bernardo Silva and Ilkay Gundogan ended Aston Villa's resistance as Manchester City moved top of the Premier League for the first time this season - for a couple of hours before neighbours United regained the leadership.
Pep Guardiola's side were knocked off the summit later on Wednesday as Manchester United beat Fulham, but the determination they showed to claim their sixth successive league win underlined that they are here to stay in this title race.
Villa's first team, playing their first game since New Year's Day because of a coronavirus outbreak at the club, showed no after-effects of their 19-day hiatus and produced a dogged defensive display.
They held out until the 79th minute, when Rodri controversially stole the ball off Tyrone Mings and fed Bernardo, who brilliantly fired into the top corner from the edge of the box.
Rodri was offside before he returned to an onside position to challenge Mings and Villa manager Dean Smith was sent off for his protests.
It meant he was not there to see Gundogan make sure of the points from the spot soon afterwards after Matty Cash handled a Gabriel Jesus header, in what was a far more straightforward decision for referee Jon Moss.
City's perseverance pays off
For long spells on a miserable night at Etihad Stadium it appeared that City's breakthrough would never come.
Things might have been more straightforward for City had Bernardo converted from close range when a corner was headed into his path after four minutes, but instead Emiliano Martinez made a brave save at his feet and set the tone for a battling Villa performance.
City had 24 efforts at goal before Bernardo eventually broke the deadlock, but 12 of them were blocked and the closest they had come to a breakthrough was when Joao Cancelo's second-half shot bounced back off the bar.
Villa rode their luck, especially when Martinez denied John Stones from a corner and the ball somehow evaded Gundogan when he appeared certain to follow up and score, but they also had chances of their own.
Bertrand Traore almost made the most of a slip by Kevin de Bruyne but his curling effort was well saved by Ederson, who also had to claw away a goalbound Douglas Luiz effort to secure his side's fifth consecutive clean sheet.
Villa vibrant on return to action
Villa leave Manchester empty handed, just as they did in their previous Premier League game against United on 1 January, but they deserve great credit for their performance here.
Nine unnamed players and five members of their backroom staff had tested positive for Covid-19 at the start of January, and the club's training ground only reopened on Sunday.
They had seen their past two league games, against Everton and Tottenham, postponed but this was a reminder of the way they were playing before their season was interrupted.
Smith was December's manager of the month after his side stayed unbeaten across five games and ended the year in fifth.
They have dropped out of the top half while they have been out of action but on this evidence that is a false position - the defensive improvement that has been the hallmark of their season was again on show here, as was their spirit.
-- Courtesy of BBC Sport