Arsenal seeks to improve their game following their sloppiness in the start of the season.
Tuesday’s game was calmer and impressive as Unai Emery decided to give some playing time to the graduates from the academy.
All the youngsters played to impress and be given more playing time with the squad and they made judicious use of the time given them as they trashed Nottingham Forest 5-0.
Martinelli, who joined the gunners in the summer from a Brazilian side Ituano for £7million, caught the eye with an impressive display and opened the scoring in the 31st minute before getting another in injury-time.
Rob Holding, who played his first match since injuring his knee last December, headed home from a corner and Joe Willock and Reiss Nelson got in on the act.
It was a pleasant night for Emery as youngsters like Martinelli showed his worth, while Holding, Kieran Tierney and Hector Bellerin all impressed on their returns from injury.
Indeed it was the return of Holding to the starting XI that created a buzz around the Emirates before a ball had even been kicked.
The fact Tierney was in the team too to make his debut only added to that, but in the end it was Martinelli who got fans off their seats.
Nelson picked out Calum Chambers with a cross-field pass from the left and, when the right-back volleyed the ball into the box, Martinelli was there to head into the net.
Arsenal deserved a first-half win following displays which saw Tierney impress and was only dampened when youngster Emile Smith Rowe was stretchered off.
Arsenal pushed for a second goal to kill the game, but Willock headed wide from six yards out when Bukayo Saka had picked him out.
In the 71st minute, Holding marked his return by heading home Nelson’s corner.
Arsenal had a third goal few minutes later from Willock as the midfielder slotted home a cut-back from Bellerin.
The Gunners added a fourth in the 84th minute through Nelson before Martinelli got the fifth by curling home his second from long range.