A Madrid victory ensures advancement to the knockout stage, while a draw will also be enough if Galatasaray does not lose at Copenhagen.
Madrid: Here are five things to know ahead of Tuesday's Group B matches in the Champions League, with Real Madrid visiting Juventus and FC Copenhagen hosting Galatasaray:
Juventus be warned, Real Madrid's attack is so potent it is making opponents cry. Cristiano Ronaldo has scored 20 goals in 15 matches, and the Portugal forward needs only one more in the next three games to match the group stage record of eight in a season, held by Ruud van Nistelrooy, Filippo Inzaghi and Hernan Crespo.
Ronaldo has had help from teammates Karim Benzema and Gareth Bale, who turned provider for three of his last five goals.
The Wales winger has scored two goals himself this week. Rayo Vallecano defender Anaitz Arbilla was in tears moments after Bale easily beat with him with a playful touch en route to a goal on Saturday.
A Madrid victory ensure advancement to the knockout stage, while a draw will also be enough if Galatasaray does not lose at Copenhagen.
Madrid's visit is just the start of a testing week for Juventus.
The team, which needed a late strike from Paul Pogba to beat Parma 1-0 Saturday, is three points behind leader AS Roma before Sunday's game against Napoli. But first up is Madrid, with Juventus knowing defeat could all but end its chances of qualifying for the next stage of the Champions League.
"If you're off top spot, even after two back-to-back titles, people talk about problems. We're perfectly calm as we've always responded positively," Juventus midfielder Claudio Marchisio said.
"(At Madrid) Giorgio Chiellini's sending off changed the game, but even when down to 10 we played an excellent game in terms of our attention and chances created. We must do this again on Tuesday night."
Madrid coach Carlo Ancelotti has warned his players to drop their egos and get back to basics after a "disastrous" defensive performance in a 3-2 win at Rayo.
"We need an attitude change," Ancelotti said. Madrid's defense seemed to implode after Pepe caused a penalty, with an undisciplined tackle from Marcelo two minutes after that allowing Rayo to claw back into the game.
Goalkeeper Diego Lopez, who should give way to Iker Casillas against Juventus, kept Madrid from dropping points as the team appeared disorganized and inept over a frantic final half hour.
"We're all feeling a little down about it, it's happened (in two straight games)," Pepe said. "The most important thing is to recognize it ... and make sure it doesn't happen again."
Juventus is counting on its local support and impressive home record against Madrid. The new Juventus Stadium has proved somewhat of a fortress in the Champions League with Bayern Munich the only team to emerge victorious in Turin. In its old stadium, Juventus had lost only twice in the competition in 10 years.
"In Turin, we'll be able to count on the support of our fans, who will provide a red-hot atmosphere at the stadium," Marchisio said. "We haven't had a great deal of time in which to prepare for the game, but encounters like these provide plenty of motivation by themselves."
Madrid hasn't won at Juventus since 1961-62. Since then, Juventus has racked up five straight wins over its Spanish rival. The last time either team won away was 1986 when the Italians won at the Bernabeu.
Galatasaray can take a big step toward reaching the knockout stage, but it will have to do it without two key players.
Goalkeeper Fernando Muslera is likely to sit out the trip to Copenhagen with a broken toe, leaving backup Eray Iscan to make his first appearance since undergoing knee surgery in September.
Wesley Sneijder's nagging right thigh could also keep the Netherlands midfielder from taking part.
The Turkish club can take a big step toward advancement with a victory, but Copenhagen is unbeaten at home in the group stage over the past eight seasons, including a 1-1 draw against Juventus this season.