“The team was upset," he told TNT Sports Brasil. "Obviously he's a player that will be missed in any club.
"He's gone to a big club and is working to achieve his goals. And we're conscious of the big group we have here, we're working hard every day to improve. Everybody's here to help and that shows in games."
Diaz also opened up on the Reds' tough start and what's been missing for the team in the first part of the season.
Diaz continued: “It's simple. Win, win and win. I think winning gives you much more confidence, but not only that, to play well and leave the pitch with the impression you gave your all. For me that's the most important thing.
"But when that doesn't happen, we have to try and improve in training to try and rectify in the next game. We've very happy with the win tonight, now we'll rest to prepare for what's coming."