Cristiano Ronaldo says there was no excuse for Juventus' 3-0 home defeat to Fiorentina but is optimistic the Serie A champions will "come back stronger and more united than ever" in 2021.

The Turin giants suffered their heaviest loss since moving to the Allianz Stadium nine years ago as the lowly Viola pulled off a shock victory on Tuesday.

Juve were already a goal down following an opener from Dusan Vlahovic when Juan Cuadrado was sent off after only 18 minutes for a challenge on Gaetano Castrovilli.

Alex Sandro's own goal and Martin Caceres' simple finish sealed it for Fiorentina, leaving Andrea Pirlo's side seven points behind leaders Milan in fourth place at the end of the year.

Prolific forward Ronaldo knows their display was unacceptable and called on the Bianconeri to regroup for the remainder of the season.

The Portugal captain posted on Instagram: "Yesterday, with a poor performance and a result far from acceptable, we closed our scheduled games for 2020, a special year in many particular ways. Empty stadiums, COVID protocols, postponed games, long stoppages and a very tight calendar.

"But this is no excuse for anything. We know that we have to give more of ourselves, in order to play better and to win in a more consistent way. We are Juventus! And we simply cannot accept anything less than excellence on the pitch!

"I hope this short stoppage may help us to come back stronger and more united than ever, because the season is still far from over and in the end we believe that we will, once again, celebrate with our tiffosi.

"Believe in us, trust our team as much as we trust you, and we will deliver!"