The Champions League got very interesting this week with a number of matchups remaining rather ambiguous at best. The 3-0 win for Real Madrid over Borussia Dortmund is no longer a contest at this point. Dortmund would need to win 4-0 or 5-1 in order to progress against the Spanish League giants; Madrid has conceded a total of seven goals in the entire tournament to date and looked completely unstoppable in the first leg. More to the point, Jurgen Klopp's troops looked lost for answers and rarely produced any scoring chances against Madrid.

The other ties are far more interesting. Paris Saint-Germain won 3-1 at home in the first leg and while the score would indicate that the team is the heavy favorite to play in the semi-finals, it is impossible to simply write off Jose Mourinho. His team needs a 2-0 win at home to clinch a spot in the semi-finals; the team has managed to pull off a plethora of impressive wins at home by lopsided scores. The other major X-Factor in this game is the health of Zlatan Ibrahimovic. The Swede was injured in the match and failed to score for the second straight UCL match. His absence could be a huge hit to an offensively-oriented PSG. One must not overlook the fact that two of the goals were the result of bad Chelsea defending rather than great plays from the French contingent. PSG's other big forward Edinson Cavani played woefully in this game and his recent complaining could hurt his side more than it will help it. This match could still go Chelsea's way with the right luck and play at Stamford Bridge.

The other two matches are toss-ups. Manchester United is still the underdog against Bayern Munich at the Allianz Arena, but there is still a glimmer of hope for the English side, especially after the team's performance in the first leg. Munich should come out on top but a repeat of Tuesday's performance next Wednesday could prove disastrous for Pep Guardiola and company. It will be interesting to see if the absence of Bastian Schweinsteiger hurts the team in any way; the side has played without him for long stretches, but the psychological impact of seeing him sent off could lead to a more cautious display from the German side. That would not work out.

The Atletico Madrid-Barcelona tie is the one that is almost impossible to predict. The teams have met four times this year and have only scored two goals each in those four matches; every single game ended in a draw. Neymar has scored both goals for Barcelona while Diego and David Villa were the scorers for Atletico. The game is headed to the Vicente Calderon, giving los Colchoneros a clear edge. Furthermore, the team has an away goal and can play for a scoreless draw. This puts tremendous pressure on Barcelona to score and could potentially expose them defensively.

Which Champions League semifinal is most exciting heading into the second leg?