Dusan Vlahovic (2) and Francisco Conceicao struck for the visitors, with Benjamin Sesko scoring twice for RBL. Juve also had to play for the final half-hour with 10 men after goalkeeper Michele di Gregorio's dismissal.
“We played well in the first half too, even if there were a few technical errors, but we did even better when going down to 10 men,” Motta said afterwards.
“I think the difference in the second half was that we had more belief and wanted to prove our superiority on the pitch. The first half was good, but in the second we needed to prove that we were superior to our opponents and therefore deserved the victory.
“The courage was shown by my players, not by me, so they deserve the credit. The team gave the feeling it genuinely believed in what we had talked about before the match.
“These players wear the jersey of an important club, so this is the mentality they ought to have. The lads showed their pride and determination, for all the staff who work with them, all the fans who were here tonight and who watched at home. We have to transmit that desire, commitment and determination.
“I am glad for the team, because it was a difficult match with some negative situations, but we reacted to those very well.”