Arsenal put in another strong display to comfortably see off Bodo/Glimt in the Europa League at the Emirates.
Fabio Vieira crossed it in for Rob Holding to head in a second before the Portuguese made it 3-0 late on.
Mikel Arteta's side have won four successive matches in all competitions and top their Europa League group, as well as leading the Premier League.
They looked like a team playing full of confidence in the first half despite Arteta making eight changes from the side that beat rivals Tottenham in the weekend's north London derby.
Nketiah, who also scored in the 2-1 victory over Zurich in September, came into the team and was a threat throughout.