Premier League talking points: Nketiah's rise, mid-table giants and Haaland hits 30
But Manchester City and Erling Haaland reminded the Gunners that the champions will not relinquish their title without a fight as the Norwegian's hat-trick beat Wolves 3-0.
United's defeat and a goalless draw for Newcastle at Crystal Palace opened the door for Liverpool and Chelsea to close on the top four, but neither side could find the net in a drab 0-0 draw at Anfield.
At the other end of the table, seven points separate the bottom seven as West Ham were the only winners among that group with a 2-0 victory over Everton.
AFP Sports looks at three talking points from the Premier League weekend.
Nketiah rises to the challenge
When Gabriel Jesus suffered a knee injury at the World Cup, many Arsenal fans feared their Premier League title hopes could be fatally undermined.
But Nketiah has risen to the challenge in spectacular style.
Jesus, who arrived from champions Manchester City last July, revitalised the Gunners' forward line, bringing title-winning belief and swagger to a side that had not mounted a sustained title charge for many years.
In his absence, Nketiah has become the main man in the Arsenal forward line, scoring six goals in six games in all competitions since domestic football resumed after the World Cup.
The 23-year-old's two goals on Sunday took him top of Arsenal's goalscoring charts with nine for the season -- one ahead of Bukayo Saka, who also turned in a dazzling performance in London.
For so long a bit-part player, Nketiah now has 13 goals in his past 13 starts at the Emirates.
Mid-table reality for Liverpool, Chelsea
A repeat of last season's League and FA Cup finals began and ended the weekend as a clash between the sides ninth and 10th in the table.
A third consecutive 0-0 draw between Liverpool and Chelsea did little to aid either side's case to charge up the table into contention for the top four, but the quality of the performance was arguably even more concerning than the result for Jurgen Klopp and Graham Potter.
On a frigid January afternoon, there was precious little goalmouth action to get the crowd excited at Anfield as Liverpool failed to win for a third consecutive league game.
Chelsea have won just two of their last 10 matches in all competitions as both sides sit 10 points adrift of the Champions League places.
For the Blues, a bright debut off the bench by Mykhailo Mudryk does at least offer some hope for the future.
But there is little sign of life from a Liverpool side that appears worn out by the challenge of keeping pace with City in the battle to be top dogs in the Premier League over the past four years.
Haaland hits 30
Haaland has needed just half a Premier League season to already surpass the 23 goals that saw Mohamed Salah and Son Heung-min share last season's Golden Boot.
The Norwegian's fourth hat-trick of his debut season moved Haaland onto 25 league goals in just 19 appearances.
Across all competitions, the 22-year old is already up to 31 goals for the English champions.
"He just keeps coming up with the goals. He's incredible. He's probably got more than me in my career in half a season," said City defender John Stones.
"What a great professional and incredible player."