Rafael Benítez's Chelsea game changers leave Manchester United swamped

Spaniard's substitutions enabled Ramires, Oscar, Eden Hazard and Juan Mata to overload their opponents in the central areas

It was not quite Istanbul 2005 but for the first time as Chelsea's interim manager Rafael Benítez changed the course of a game via the bench. The Spaniard has frequently been criticised for his poor use of substitutions – a right-back for a right-back when chasing matches was a particular source of frustration – but here Chelsea dominated the second half after Benítez's double switch.

The inevitable question is whether he should have got things right from the outset, and his starting selection was surprising, even taking into account the need for rotation. In particular, a mobile central midfield duo of Ramires and Frank Lampard was peculiar against a United side that uses a dangerous attacker – on Sunday, a reinstated Wayne Rooney – behind their main striker.

Benítez's favourite buzzword is "compact" but in the opening stages Chelsea were a rabble, strung out across the Old Trafford pitch. The centre-backs were terrified of Javier Hernández's pace, so dropped deep (which wasn't enough to prevent the Mexican opening the scoring), forcing the midfield to cover too much ground and leaving Demba Ba with little support.

United's own sloppiness unquestionably contributed to Chelsea's second-half dominance – the number of times they conceded possession within their own half was extraordinary – but Benítez's changes certainly helped. Replacing the peripheral Victor Moses with Eden Hazard had an immediate impact with the Belgian's superb curler, but introducing Mikel John Obi in place of Lampard was actually a more effective change.

That switch was surprising on paper – Benitez would have been castigated for his negativity had Chelsea not completed their comeback. But Mikel's permanent stationing in the holding position stabilised Chelsea and, more importantly, allowed Ramires to charge forward with typical energy – he had made a similarly dangerous run shortly before his equaliser, having previously remained cautious alongside Lampard.

The Brazilian combined with Juan Mata, Hazard and Oscar, who were able to interchange positions and overload Manchester United in central positions, as United were desperately outnumbered in midfield. Rooney, quiet after his goal, demonstrated why Sir Alex Ferguson didn't trust him defensively against Real Madrid in midweek, failing to contribute without the ball and forcing his manager to change United's system.

Rooney was moved out to the left flank, with Kagawa brought into the centre after Robin van Persie's introduction – but United did not improve, and for the second time in a week the opposition coach's substitutions prompted a strong second‑half showing.