Arsenal's Gabriel Martinelli, second left, scores his side's second against Standard Liege. Photo: Matt Dunham/AP Photo

Arsenal manager Unai Emery hailed forward Gabriel Martinelli's hunger and aptitude after the Brazilian teenager fired in two goals and set up another in Thursday's 4-0 Europa League win over Standard Liege.

The 18-year-old, who joined Arsenal in the close season for a reported fee of 6 million pounds ($7.40 million), struck twice in two minutes in the opening half and set up Dani Ceballos to cap off an impressive display at centre forward.

"He played in this position with us and in every training he showed us his hunger to be with us," Emery told reporters.

"In pre-season he played in different positions, but above all he preferred playing on the left wing. But also he played as a right winger.

"I used him as a striker because in Brazil he played this position. It's not the best position for him, but the first (thought) in his mind is to help us... his performance and aptitude was amazing."

Martinelli's brace followed a two-goal haul in their 5-0 win over Nottingham Forest in the League Cup last month and defender Hector Bellerin said the Brazilian was reaping the rewards of following Emery's advice in training.

"Everyone is pleased for him," Bellerin, who made his first start on Thursday after nine months out with a knee injury, told BT Sport.

"He has been a player, he keeps his head down, he works really hard, he is doing what the coach wants him to do and it shows on the pitch."

Joe Willock, 20, was also on target on Thursday for a youthful Arsenal lineup with an average age of 22.

"Historically Arsenal have that responsibility with young players, and... my responsibility now is also speaking with the club and giving them chances," Emery added.

"We want to give them chances, but we need to find our very high demands in our performance to achieve our targets. We're in one process and we want to do it as quickly as we can because our targets for the season are very important to achieve."

Reuters