Manchester United vs Real Madrid 2013: Defense Will Be Key in Electric Duel

The last time Real Madrid faced Manchester United in Old Trafford, Ronaldo scored a hat trick, but two late goals by David Beckham gave the home club a thrilling 4-3 victory.

Of course, that was in April 2003, and this is nearly 10 years later.

Still, it wouldn't be out of the question for the score to look similar on Tuesday as the two clubs face off in the second leg of the Round of 16 in Champions League play.

United—led by Robin van Persie—has scored a Premier League-leading 68 goals in 28 matches this season. That's in addition to the 10 goals in seven Champions League matches.

Real—led by Cristiano Ronaldo—has scored 64 goals in 26 La Liga matches, second to Barcelona. That's in addition to the 16 goals in seven Champions League matches.

Both United and Real's strengths lie in their attacking ability. They haven't been awful on defense, but there are certainly some holes in their back end that can be exposed.

Top goalkeeper Iker Casillas will not be available for Real in the clash, which is certainly worth monitoring. In the two clubs' Feb. 13 Champions League encounter, United managed six shots on goal—Casillas saved five of them.

Ronaldo—who scored the lone goal for Real in that match—has been fantastic in Champions League play, with seven goals and one assist in seven matches. Teammate Karim Benzema has three goals and two assists in six matches (five starts). 

On the other hand, Van Persie had made an impact in Champions League play as well, with three goals in five matches (four starts). There's also teammate Wayne Rooney, who has posted one goal and three assists in five starts. Javier Hernandez rounds out the dangerous group with three goals in six matches (five starts).

One thing's for sure: It figures to be yet another high-powered affair between United and Real on Tuesday. Get ready to watch some brilliant action around the net.