Three years on: all pointers say Chelsea

Who better than the best player on the planet to assess whom we should favour as Chelsea and Manchester United prepare to resume a European battle last decided by a game of Russian roulette in Moscow's Luzhniki Stadium, nearly three years ago? "Barcelona, Madrid and Chelsea are the favourites for the Champions League," Lionel Messi said before the quarter-final draw. That the bookmakers should have agreed with him confirms the lingering suspicion that United, despite being top of the Premier League, are just not the team they were when they won the penalty shoot-out in the 2008 Champions League final and that, for all the thrilling comebacks that have characterised their past eight months, their number will be up when they reach the highest plateau of the season so far.

The numbers certainly do tell a story. Since the night Chelsea trudged away so disconsolately from the Luzhniki pitch, they have invested £126.1m on players, while United have spent only £75.9m. Even Sir Alex Ferguson acknowledged, four days ago, that Chelsea are the ones spending for Europe. Had injuries not intervened, United's team-sheet might have included just two changes from Moscow – the absentees being Carlos Tevez and Cristiano Ronaldo, whose sale at £80m earned United almost three times Chelsea's entire transfer-market income since the final.

The starting line-ups in west London tomorrow may actually include seven apiece of the 2008 sides, if Carlo Ancelotti opts for Didier Drogba and foregoes the logical option of exposing Nemanja Vidic to the perils of Fernando Torres, a player who terrorised the Serbian defender in a way that will always remain with him when Liverpool visited Old Trafford in March 2009. But despite the continuity of personnel, Chelsea now look the more dominant force. Ryan Giggs at left-back might have been a quaintly effective sight at Upton Park but it won't do at Stamford Bridge, with United's defensive injury problems looking chronic. The absences of Rio Ferdinand, Wes Brown, John O'Shea and Rafael da Silva may expose Rafael's twin, Fabio, to the task of marking Ramires, while Chris Smalling – United's third most expensive player since Moscow but one still under development – faces the rapier pace of Torres or Drogba. Aside from those occasional wild challenges he is prone to, Chelsea's £21m David Luiz offers far fewer grounds for uncertainty.

There are also persistent doubts about United's midfield. Michael Carrick and Paul Scholes may well be asked to run it, just as on 21 May 2008 in Moscow, but the poise of their display together in the first half of their league game away to Chelsea on 1 March did not really tell the story of United's season. The second period, as Michael Essien, Frank Lampard and Ramires overran the midfield and drove Ancelotti's side on to their 2-1 win, was rather more typical of what United's fans have been observing up and down the land. Ferguson continues to remember referee Martin Atkinson's leniency towards Luiz, where that occasion at Stamford Bridge is concerned, though the impact from the bench of Yuri Zhirkov – another of Chelsea's five £15m-plus players since these sides last met in Europe – was far more significant.

Both Vidic and Carrick admitted yesterday that such a recent league victory for Chelsea on home soil could be psychologically significant. "Maybe, in terms of the results, it is," Vidic said. "In the last few games, they had good results [against us] so yes... it helps [them]." In the five games between the sides since Moscow, United have won only once – the 3-0 victory days before Luiz Felipe Scolari's sacking early in 2009. "We've actually played all right at times but it doesn't count for anything, it's all about results," Carrick said.

Yet, for their own part, United can take encouragement from Chelsea's own inconsistency of recent months and the fact that both Drogba and Torres have struggled for goals since the latter joined Chelsea on 31 January. And then there is the most intriguing factor perhaps beginning to weigh in United's favour: the cumulative effect of their extraordinary pattern of comebacks. United have fallen behind so often this season that even a trip to West Ham carries omens ahead of it. But in this season of imperfections, Ferguson's influence has been more telling than ever. He has been called on to make many more direct interventions in games than we have been accustomed to – he is on course to make 140 substitutions this season, 20 more than in the last campaign – and to judge by Giggs's fascinating testimony about what went on in the dressing room at Upton Park at half-time, the manager is operating with more serenity than previous generations have known in him. "No, no, no, calmness," Giggs said, when it was suggested that Ferguson had combusted in the dressing room. "He just said 'concentrate a bit more'."

Victory for United over the course of the two legs in the next seven days would certainly represent a triumph for Ferguson's creed of investment in those young players he sees and has trust in. Only two of Ferguson's signings since Moscow have cost more than £15m, while only one of Chelsea's has cost less than that.

If fate has Javier Hernandez marked out as the hero of this particular hour, rather than Torres, a player whose transfer fee was more than eight times that of the Mexican, then it will be a reaffirmation that investing in youth can pay off in Europe. The average age of the probable Chelsea side for tomorrow night is 28 years and four months, while United's may be just 23 years and nine months.

All of which is the story on paper. Messi, of course, is rather more aware of the practical matters of the pitch and, just as he has told it, the weight of probability as well as the vast weight of investment tells us that Chelsea ought to make the next huge step towards Wembley.