The 23-year-old has endured a truncated career with L'OM since joining from Monaco in 2014 and spent the first half of last season on loan at Genoa before switching Serie A clubs to join Milan from January to June.
However, he returned to the Stade Velodrome during the summer and has enjoyed an excellent start to the Ligue 1 campaign, scoring four goals from five appearances.
The Argentine winger has become a key member of Rudi Garcia's side and he is clearly enjoying playing under the present Marseille boss.
He told La Provence newspaper: "It's just a start as I've only played five league games. My objective is to keep at this level all season long.
"I had a bad year here when Michel was coach. The last two months have been great for me. Things are going well and I'm beginning to feel important."