"I am feeling a bit tired but I'm so happy with the goal and even happier with the victory and the three points," Martinelli told the club's website after the game.
"I work every single day in training, you need to prepare yourself because when Mikel needs you, you need to be there to play and show something."
The Switzerland midfielder had to fill in at left-back against Sheffield United, helping his side clinch a clean sheet in the 3-0 victory.
"I thought it worked really well," Arteta told the club's website.
"Obviously we need some work on that and I have the feeling that Granit can develop into a really good full back for what we require in certain games to do."