At 18 years and 125 days old, the forward became the youngest player to start a match between the two sides in the Premier League.
The Gunners manager was full of praise for Saka, who assisted Pierre-Emerick Aubameyang as his team held the Red Devils to a 1-1 draw at Old Trafford.
GOAL Man Utd 1-1Arsenal (58 mins)— Premier League (@premierleague) September 30, 2019
Saka releases Aubameyang who races through and tucks the ball into the back of the net#MUNARS
When asked about the Anglo-Nigerian’s impact, the Spaniard did not mince words in acknowledging his huge potential and importance to Arsenal squad.
"I think he's working and improving, being mature and also playing matches in front of each player and each team as tonight against Manchester United," Emery was quoted by Arsenal website.
"But his work is natural and he is improving. He is helping us now as an important player.
“We are going to work with him with him with calm, with patience, but if he deserves to take minutes and to take confidence for helping us with his performance, that is fantastic for us."
The England youth international was a constant threat to Ole Gunnar Solskjaer side's backline before his replacement by Joe Willock after 80 minutes.
He is expected to be on parade when the Emirates Stadium side host Standard Liege on Thursday.