But the youngster is now set to be back on the bench at Burnley on Sunday.
Sarri said: “Ruben played very, very well. At the beginning of the season, I told him he was a really good player, now I think he is more suitable to my football.
“He’s improving. But he needs to improve the defensive phase. At the moment we have four midfielders for two positions, and three of them with the same characteristics. It is very difficult for me to put in four offensive midfielders of the same character. I need an improvement in the defensive phase.
“But I like this kind of problem. I can only put 11 players in the starting side, but I have 28 players. I know the fans love him, of course, because he was in the academy. It’s normal. My problem remains the same.