The former Manchester City manager saw his new side beaten on Sunday by newly promoted Akhisar in the Super Lig and demands an immediate improvement from his squad
Omar Niasse scored twice for the hosts - either side of half-time - meaning that Didier Drogba's strike with 23 minutes to go turned out to be just a consolation goal.
The Italian took over the reins at the end of September and bagged a hard-fought draw against Juventus in the Champions League in his first match in charge at the Turk Telekom Arena, though he is aware that success domestically will require more graft than was seen in Sunday's loss.
"[Akhisar] scored two very important goals due to us making mistakes and, at this level, a team should not be conceding like that," he told Lig TV after the match.
"Something that is missing is that a few of the players lack experience. On the pitch we must try to fight more.
"Three or four times the team's shortcomings were made obvious. During the international break I will evaluate what I thought went well. But we must raise our level."
Galatasaray sit one point off the relegation zone and eight points behind Lig leaders Fenerbahce with six games played in 2013-14.