Madrid-Manchester United, Beckham headline Champions League

The Champions League round of 16 second-leg ties get under way this week, and the biggest game is at Old Trafford, where Cristiano Ronaldo returns to his former club to take on Premier League champions-elect Manchester United. German champion Borussia Dormtund is a slight favorite after a first-leg 2-2 draw at Shakhtar Donetsk, while on Wednesday, first-leg victors Paris Saint-Germain and Juventus are expected to make the final eight. Here is the rundown of this week's matches as the competition reaches a dramatic phase:

Real Madrid at Manchester United, Tuesday, 2:45 p.m. ET

First Leg: 1-1

If this is the defining week of Manchester United's season -- with the Premier League title almost won, it follows up this tie with an FA Cup match against Chelsea this weekend -- then this is also the defining match of Jose Mourinho's three-year spell at Real Madrid. There seems no doubt that he will be leaving the Spanish capital at the end of the season: the question is, will he have fulfilled his brief when taking the job, or not?

There were two things Mourinho was tasked with on his appointment: firstly, ending Barcelona's era of dominance and secondly, winning the Champions League, for la decima, the 10th time in Madrid's history. Even though Barcelona is running away with La Liga, Mourinho has effectively managed the first job.

Last week, Real Madrid beat Barcelona 3-1 at Camp Nou in the Copa del Rey semifinal second leg, and on Saturday, it beat Barca 2-1 in the league. It was Mourinho's fourth win in his last seven games against Barcelona, and the first time Madrid has won consecutive games in the clasico since before the Pep Guardiola era.

"If the objective in hiring Mourinho was to slay the dragon, mission accomplished," wrote columnist Juanma Trueba in AS.

The second task is even tougher: in the last two seasons, Madrid has reached the Champions League semifinal, losing to eventual winner Barcelona in 2011 and Bayern Munich, on penalties, in 2012. Mourinho was confident after the first leg against United, suggesting that a score-draw at home might not be so bad; given that United, in the second half, had three good chances to win the game, he may have had a point.

Sir Alex Ferguson has a tactical dilemma on his hands: push forward for the win, and invite Madrid to attack on the break, where it is most dangerous, or sit back knowing that a goalless draw will be enough to progress? It's not his style to play defensively, and that could be United's downfall. But to allow Cristiano Ronaldo any space at all on his return to Old Trafford could be dangerous.

As for Mourinho, given that he has fallen out with his players, the fans, his board and journalists who cover the team, this game might even be his last in charge. It's typical Mourinho to build the pressure up on himself and then get his team to deliver a masterful performance: that's what happened last week in Barcelona, and it could happen again in Manchester.

Tip to progress: Real Madrid

BERLIN: Spurs topple Arsenal without Dempsey

Shakhtar Donetsk at Borussia Dortmund, Tuesday 2:45

First Leg: 2-2

Is Borussia boss Jurgen Klopp beginning to believe his own hype? After the German champions lost to Bayern Munich in the Cup last week, Klopp accused his rival of copying Dortmund's style of play. Bayern boss Jupp Heynckes was furious.

"Bayern has been around longer than Klopp and has always had its own style," he said. "It's important to remain humble in victory or defeat. I've beaten some of the greatest coaches: (Marcello) Lippi, (Arrigo) Sacchi, (Ernst) Happel and (Johan) Cruyff. They never turned around and said I copied them."

Dortmund has at least recovered from its rocky start to the season and has now moved up to second in the Bundesliga: it won't overhaul Bayern's massive lead, but a second place and a decent run in the Champions League would represent a fantastic season for the reigning German double-holder. There are worries going into this game, though, that Mats Hummels won't have recovered in time from a flu bug. Felipe Santana is on stand by, but German pundits are nervous that Shakhtar's new playmaker, Taison, impressive on his debut in the home leg, will run rings around his compatriot. One thing seems sure: despite the two away goals Dortmund scored in Donetsk, it will still go for the home win on Tuesday.

"We will play our natural game," captain Sebastien Kehl said. "To play for the draw, that's not our style."

Tip to progress: Dortmund

Valencia at Paris Saint-Germain, Wednesday, 2:45

First Leg: 2-1 PSG

PSG sports director Leonardo infuriated senior figures in French football after the team's second successive away defeat to a team fighting relegatio. After losing 3-2 at Sochaux last month, the French leaders lost 1-0 at Reims on Saturday, to which Leonardo responded: "This team is built for Europe, not for these types of games."

Leonardo has a point (I have been saying the same thing all season), but his comments could not have gone down any worse in France.

"What an unbearable lack of respect," RMC Radio pundit Jean-Michel Larqué said.

"His comments have not been appreciated in places of power," Lille president Michel Seydoux said. "In any case, whether in football or as the French capital, Paris has this image of arrogance."

Zlatan Ibrahimovic may have earned the headlines after the first leg with a late red card that rules him out of this tie -- and the first leg of the quarterfinal, if PSG progresses -- but the marquee act for this game could be a 37-year-old Englishman whose last Champions League game was seven years ago.

David Beckham watched the win in Valencia from the stands but made an assured first start in PSG's 2-0 Cup win over Marseille last week. He played alongside Blaise Matuidi and brought some composure to the midfield. He might not start this game but will play some minutes; his job will be to get the ball to Lucas Moura, whose first-leg performance, in his Champions League debut, was electric. Ibrahimovic may struggle to light up this competition, but PSG has a new star in town now.

"I can't think about winning the Champions League again, because it is too far away now, but the simple fact of playing in it again after having been away for seven years, is incredible," Beckham told L'Equipe last week.

Tip to progress: PSG

Celtic at Juventus, Wednesday, 2:45

First Leg: 3-0 Juventus

Juventus has already played its biggest game of early March: The Italian leader tied second-place Napoli 1-1 on Friday, maintaining its six-point advantage at the top of Serie A. The Italian side had shown signs of vulnerability before the first leg tie -- it has won only four of its last nine league games -- but was clinical in taking advantage of two Celtic mistakes that led to goals that this tie is as good as over despite Juventus protestations to the contrary.

Instead, the buildup has focused on the future of Juventus coach Antonio Conte, reported by Tuttosport to be wanted by Real Madrid and Chelsea next season. "The coach is set on staying, especially if the club build an even stronger side," writes the paper. Juventini will certainly hope that's the case, and he recently got the backing of club director Pavel Nedved.

"Conte is a true star," Nedved told the official Juventus website. "To become a top coach you have to be able to get your ideas across to the players, to get your personality across. He knows how to do that. He hasn't won as much as Lippi and (Fabio) Capello, because he is younger than them, but he'll no doubt catch up with them. He's one of the best."

Tip to progress: Juventus

DART: MLS first impressions