Juventus coach Ciro Ferrara defended his players after their uninspiring 1-0 Champions League victory over Maccabi Haifa.
Giorgio Chiellini's header was enough for Juve, with Maccabi Haifa also seeing a player sent-off.
"We are a work in progress and can certainly improve, but tonight we were effectively using this system for the first time," said Ferrara.
"One must also consider in the last six years the team has always used a basic 4-4-2 that the lads knew perfectly. We changed this season and so some difficulties in adapting are inevitable.
"At this moment in time I think the team needed this system and the trio supporting the striker with [Momo] Sissoko and Felipe Melo protecting the defence.
"The fact we didn't close it down and therefore ran risks at the end, that is something we need to improve. A great squad knows how to hold on to the ball and the initiative, especially against 10 men."
Diego played as part of a supporting trident behind David Trezeguet, flanked by Mauro Camoranesi and Sebastian Giovinco.
Ferrara added: "He still needs to get to know his teammates and the Juventus environment, but that's normal. I think he had a good game tonight and we are confident and he found his place between the lines very well along with working hard."