Pepe has battled for consistency since his summer arrival from Lille.
But Arshavin, speaking exclusively to 888Sport, said: “Pepe is a very talented player. He is very quick and a good finisher. Already he has done well in part: maybe not as much as he could but I see the potential and he will become one of the biggest stars in the Premier League. He will be huge."
And on Martinelli, the Russian added: “At the moment it is difficult to say but he has done well so far, scoring some good goals. He is very technically gifted and I see a big future for him at Arsenal. But can he reach the level of Thierry or Robin? That is difficult to say."