"We made some mistakes at the end of the match and we were sometimes vulnerable," said Juventus coach Massimiliano Allegri.
Isco curled in a terrific free-kick just before half-time at the Santiago Bernabeu, with Bale powering in a second and Mariano Diaz striking late as Real made a convincing start to their Group G campaign.
The 27-year-old is a popular figure in the Spanish capital due to a memorable goal he scored last season.
"The Roma squad is bigger and better than last season, and they're going to make things difficult for us," Lopetrgui said.
Roma have pledged to auction off five match-worn jerseys from their opening home game to raise money for the flood victims.
The Gialorossi aren't impressed with United and Bayern's Twitter banter.
The 23-year-old midfielder arrives in the Italian capital on the back of a burgeoning reputation.
The French tactician took charge of his final Premier League game with the Gunners on Sunday.
The Giallorossi clearly aren't one to hold on to grudges, as their latest tweet has proved!
The Serie A outfit gave Jurgen Klopp's Liverpool an almighty scare on Wednesday night.
