Victory tonight may serve only to blur the bigger picture for Chelsea

Beating Benfica will trigger ominous fixture logjam. By Sam Wallace

Roberto Di Matteo has overseen six victories for Chelsea (Getty Images)

It is the start, tonight, of potentially 12 games in the space of just 40 days for Roberto Di Matteo who, when the season is over, would still expect to find himself in the figurative wilderness when it comes to his management career.

As the only English club still involved in European football, and the only one with a stake in three competitions, a gruelling run of games awaits Chelsea if they are successful in carrying their 1-0 advantage from the first leg and eliminating Benfica at Stamford Bridge tonight. Those 12 games include a prospective Champions League two-legged semi-final and potentially the FA Cup final on 5 May, but not the Champions League final itself.

If Chelsea make both finals they will play 13 times in 46 days. Their penultimate Premier League fixture, away at Liverpool on 6 May, will have to be pushed back into the following midweek before the final league game of the season against Blackburn, which must be played on 13 May. The club have accepted that their bid to get the FA Cup semi-final against Tottenham Hotspur moved forward two days will not be successful.

If this had been any of Chelsea's previous eight seasons there would have been less concern about the fixture congestion, but the threat to their hitherto unchallenged status as a top-four club has transformed the picture.

The problem for Di Matteo is that the undoubted priority for his team is making up five points on Arsenal and Spurs above them in third and fourth place in the Premier League and ensuring qualification for the Champions League next season. The subplot is that an unexpected end-of-season tilt at glory in Europe and the FA Cup might just prove to be the undoing of Chelsea when it comes to finishing in the top four.

The sheer weight of playing on three fronts is the elephant in the corner. All Di Matteo's players trained last night, including David Luiz, Raul Meireles and Didier Drogba, who were injury concerns, and he will need all of them if he is to get through the next seven weeks.

A Champions League spot next season would come with winning the competition outright in May, but the more realistic route would be to finish in the top four of the Premier League. Yet should Chelsea triumph tonight they will have to play a tough sequence of three games in six days, starting a week on Sunday with the FA Cup semi-final against Spurs. The first leg of the Champions League semi-final will follow on the Wednesday. Three days later, on Saturday 21 April, they play Arsenal at the Emirates – a pivotal league game.

Di Matteo is loath to discuss it but he said: "It might become an issue at some point, I don't know. Fortunately, we have a fully fit squad which will help us in the run-in, to be able to play every player we have and give everybody a chance, an opportunity, and some fresh players as well.

"I think a lot of clubs would like to have so many games, to be involved in all these competitions. It's very demanding for the players, but we're in a good place."

Tonight, he has Frank Lampard and Meireles competing for the holding place alongside John Obi Mikel in midfield. Salomon Kalou, who scored the first-leg goal, is back in favour and likely to start on the left of the three in a 4-2-3-1 formation. There is another big call on whether to stick with the – relatively – in-form Fernando Torres over Drogba.

The injury news is worse for Benfica, who arrived without the injured centre-halves Ezequiel Garay, Miguel Vitor and Jardel.