The Premier League restart was engulfed in controversy on Wednesday when goal-line technology made an unprecedented blunder after players took the knee to protest against racism at both matches.
The English top-flight was put on hold in March due to the coronavirus pandemic and all 92 remaining games are being crammed into a six-week period.
The first match, between Aston Villa and Sheffield United, finished goalless and Manchester City won the later game against 10-man Arsenal 3-0.
The big talking point at Villa Park came late in the first half when Villa goalkeeper Orjan Nyland appeared to carry Oliver Norwood's free kick over the line.
Referee Michael Oliver's watch failed to signal the goal and the game continued.
"I don't know whether to laugh or cry," said Sheffield United manager Chris Wilder.
"Already the jokes have started.... It's all going to come out but we're pretty disappointed and we've got to get on with it."
After the match, Hawk-Eye Innovations, which runs the technology, apologised "unreservedly" over the incident.
"The seven cameras located in the stands around the goal area were significantly occluded by the goalkeeper, defender and goalpost," the company said in a statement.
"This level of occlusion has never been seen before in over 9,000 matches that the Hawk-Eye Goal Line Technology system has been in operation"
A point apiece from the goalless draw behind closed doors did not suit either side.
Aston Villa were seeking a precious win to lift them out of the relegation zone while Sheffield United are chasing a European spot next season.
Before kick-off, in front of a huge global audience, players and staff protested racial injustice for about 10 seconds in solidarity with worldwide demonstrations following the death of American George Floyd.
"In the first Premier League fixture of Project Restart both clubs hope that the act of 'taking a knee' will send a strong message of unity," the clubs said in a joint statement.
Manchester City and Arsenal players mirrored the protest before kick-off at the Etihad.
All players will wear the words "Black Lives Matter" (BLM) on the back of their shirts where names are normally printed for the first 12 matches of the restart.
"We should send one thousand million messages for black people," City manager Pep Guardiola said.
"I'm embarrassed, I'm ashamed for what the white people have done for the black people.
"It can't be solved in a few days. We have to do a lot of things for the black people that we have not done so far."
City's home win means Liverpool, on the brink of their first English top-flight title for 30 years, cannot seal the deal when they return to action this weekend.
A first-half goal from Raheem Sterling and second-half goals from Kevin De Bruyne and Phil Foden gave second-placed City a comfortable win. Arsenal's David Luiz was sent off early in the second half.
"It was important to get the first goal and after that with the penalty and the sending off it was a completely different situation," Guardiola said.
If Jurgen Klopp's team beat Everton on Sunday they will be champions of England for the 19th time if they overcome Crystal Palace at Anfield next week.
While the race for the Premier League title is a foregone conclusion, the battle for Champions League places next season and to avoid the drop are far more closely contested.
Matches are being preceded by a minute's silence in memory of the victims of coronavirus. Britain is the worst-hit country in Europe, with more than 42,000 deaths.
Three of the four managers to lead their sides on Wednesday have been touched by the virus.
Aston Villa boss Dean Smith's father died, while Guardiola lost his mother.
Guardiola's former assistant Mikel Arteta returned to the Etihad for the first time as Arsenal manager three months after his positive test for coronavirus hastened the season shutdown.
With all games being played behind closed doors, players will have to get used to the eerie silence in the usually raucous stands.
Piping crowd chants into stadiums, cardboard cut-outs of supporters and live video fan walls add colour but the Premier League's chief executive Richard Masters admitted there would be something missing without crowds.