United's forwards destroy Marseille; Marcelo key for Real

Tactical observations from Champions League action this week:

Twenty years ago, when striker partnerships were still alive and well, they came in two basic forms: a big man and a quick finisher, or a deep-lying creator and a quick finisher. In the former, the finisher played off the big man, waiting for knockdowns and flick-ons; in the latter he played ahead of him, waiting to be fed with through-balls. In Manchester United's rediscovery of 4-4-2 (a slightly odd phenomenon given the agonies Sir Alex Ferguson went through to replace it), the front pair is very much of the latter kind. Javier Hernandez is lightning quick, while Wayne Rooney has reverted to the role in which he made his name, as a support striker, rather than as the lone frontman he was used as last season.

That presents a major problem for defenders. The orthodoxy playing against a rapid center forward is for a team to defend deep to deny him space behind them to attack. Do that, though, and a defending side leaves space in front of the back four, between the lines of midfield and defense; give Rooney that sort of room and he can destroy sides. So from that point of view, the Rooney-Hernandez partnership looks ideal in theory -- just as the Rooney-Michael Owen partnership did for England. There must also, though, be personal chemistry, something that Owen and Rooney never had (only once did one provide a direct assist for the other); Rooney and Hernandez seem to have it, and they terrified Marseille.

So does that mean that the old-school 4-4-2 is back, and that Ferguson was misguided in abandoning it? No. For one thing, this was 4-2-3-1 in the guise of 4-4-2: intuitively, it seemed Rooney was playing just off Hernandez, in front of a midfield four, and he did go beyond his strike partner relatively frequently as you'd expect a second striker to do. But look at the heat-maps and the uniqueness of Rooney's play is revealed. He dropped so deep at times that his average position was in a line with Nani and Ryan Giggs (although Nani played far wider on the right than Giggs, who had with Patrice Evra overlapping from fullback, did on the left), so the shape resembled 4-2-3-1 with Paul Scholes and Michael Carrick effectively acting as shields in front of the back four.

And for another, all United's win did was highlight all the reasons Ferguson had for tinkering with the system in the first place. He was moved to act after the Champions League quarterfinal in 2000, in which United drew 0-0 away to Real Madrid, but were beaten 3-2 at home, their relative openness exposed repeatedly despite the comparative evenness of the game. That followed home games against Borussia Dortmund and Monaco in which United conceded early away goals that effectively eliminated them. It could easily have been a similar story on Tuesday: although United had 57 percent of possession, both teams mustered 10 shots on goal. Given a scoring draw would have taken Marseille through, that underlines how easily United could have gone out, potent as its attacking duo were. Injuries permitting, a change back to 4-3-3 seems probable for the later rounds.

Some games almost defy explanation: both sides were so haphazard defensively that it essentially became a crapshoot, in which Inter, thanks in part to the excellence of Samuel Eto'o, and in part to good fortune, prevailed. It will take a major improvement for the defending champion to go much further in the competition, but what was clear on Tuesday was how improved Inter was from the first leg.

The switch from 4-3-2-1 to a 4-3-3/4-2-3-1 hybrid made an enormous difference for two reasons. First of all, Bayern's fullbacks, Phillip Lahm and Danijel Pranjic, weren't able to push forward at will as they had in Milan because this time they had Goran Pandev and Wesley Sneijder to deal with, even if both did spend most of the night cutting infield. Secondly, the use of Dejan Stankovic as a deepish creator, sitting just in front of Esteban Cambiasso and Thiago Motta but not far enough forward to be a true trequartista, radically improved the supply to the front three.

Bayern still had enough chances to have won comfortably, and Inter still seemed mystified by Arjen Robben's propensity to cut inside, but Leonardo could take heart from a much improved performance. The aim of tactics is to tweak the percentages in a team's favor: Inter may have ridden its luck, but at least Leonardo ensured the game wasn't stacked against his side as it had been in the first leg.

In the end, it looked an easy victory for Real Madrid -- it was an easy victory for Real Madrid -- but the nature of the win, particularly the first goal, did suggest that Real's greatest strength may also be a weakness. Real had been flat in the first leg, drawn 1-1 in Lyon, and at least part of the reason was the absence of Marcelo at left back. Alvaro Arbeloa was solid enough, but it is not part of his natural game to get forward and support Cristiano Ronaldo. Without the Brazilian charging outside him, it became -- comparatively -- easy for Anthony Reveillere to counter Ronaldo.

With that partnership back in tandem for the second leg, though, Madrid was far more threatening, it was an interchange between Marcelo and Ronaldo that produced the opening goal. The question, though, is whether the attacking threat the pair offers outweighs the potential defensive deficiency. With Karim Benzema enjoying an unexpected return to form, Ronaldo seems likely to be deployed on the left in future rounds, but his inability or unwillingness to track back could cause problems against a more aggressive fullback, particularly as Angel Di Maria on the other flank is no shutter either.

Ronaldo has been exposed by powerful fullbacks before, most notably by Aly Cissokho when playing for Manchester United against Porto in 2008 (the game that prompted Ferguson's decision to use Ronaldo centrally and Rooney wide, because Rooney could be relied upon to perform his defensive work diligently), and by Michael Essien in the Champions League final the same year. Jose Mourinho persuaded Eto'o to play as an auxiliary fullback for Inter against Barcelona last season; performing a similar act of persuasion on Ronaldo might be an even tougher task.

Jonathan Wilson is the author of Inverting the Pyramid; Behind the Curtain; Sunderland: A Club Transformed; and The Anatomy of England.