Here are five things to know ahead of Wednesday's Group B matches in the Champions League:
How good is Cristiano Ronaldo at scoring goals? Good enough to ask for forgiveness for not scoring even more of them.
On Saturday, Ronaldo clasped his hands together in a penitent pose after he had drilled home a late spot kick home to seal Madrid's 2-0 win over Malaga, offering an apology to the Santiago Bernabeu crowd for taking so long to find the net.
So Juventus beware: Ronaldo will surely be seeking redemption.
"The smart people know what I wanted to say," Ronaldo said. "But that's history. Now it's a new day and I hope to do it better."
Ronaldo topped the Champions League last season with 12 goals and he leads the competition with five goals through two games this campaign. Overall, the Portugal forward has netted 24 goals in his last 20 Champions League matches.
Juventus arrives in the Spanish capital after its first loss of the season on Sunday in a spectacular collapse that saw it concede four times in the last 14 minutes to go down 4-2 at Fiorentina.
Juventus has also been hit by injuries and will be missing striker Fabio Quagliarella, who had scored in its two previous group games. Former Athletic Bilbao striker Fernando Llorente could see some much-needed playing time in his place.
"It's a massive test for us," Juventus coach Antonio Conte said. "Madrid are arguably one of the most ambitious teams. We're facing a club that really want this title, because of their history and their hunt for a 10th European Cup. I think it will be a nice challenge for us to go and compete with them."
Madrid and Juventus share 11 European Cups between them, and they have clashed 14 times in the tournament.
One of the Spanish powerhouse's most memorable moments came against Juventus in the 1998 final when its 1-0 victory ended a 32-year wait to lift the seventh of now nine European titles.
Two-time champion Juventus has had the advantage since then.
Juventus beat Madrid twice in the 2008 group phase. That came after Juventus eliminated Madrid in both 2005 and 2003.
Madrid has won five and lost two times in Juventus' visits.
Defending Madrid's goal against Juventus will mean more for Iker Casillas than just helping his team beat a direct rival for the European title.
Every one of the few matches Casillas plays is a chance to convince coach Carlo Ancelotti that he deserves to be Madrid's starter in all its games, not just the Champions League.
Casillas mentioned the unthinkable for many of his fans recently: that he will consider seeking a transfer this winter if he doesn't play more.
Casillas, however, may have more to lose than to gain. Diego Lopez continues to play well each weekend in the Spanish league. And, unfortunately for Casillas, he has been in goal in each of Madrid's recent disappointments to Juventus.
The Madrid captain will play only his fifth match of the season on Wednesday. He has played twice for Spain and started both of Madrid's wins in the Champions League, although he didn't finish the 6-1 thrashing of Galatasaray due to injury.
Former Manchester City manager Roberto Mancini guided Galatasaray to a 2-2 draw against Juventus in his first game at the helm of the Turkish team after taking over for the fired Fatih Terim on Sept. 24.
Mancini's new club now has the opportunity to move up the standings in the group when it hosts FC Copenhagen with both teams one point behind Juventus.
A victory by Galatasaray combined with a Juventus loss could put it into contention for a surprising second-place finish and spot in the knockout round.