Among all the discussion of Paolo Di Canio's political beliefs, few appeared concerned about his football philosophy – and how he would attempt to lead Sunderland to Premier League survival. Sunderland were without a win in eight matches and missing their top scorer Steven Fletcher through injury – so a trip to the reigning European champions was hardly an ideal inauguration for Di Canio.
From the opening minutes, a significant change in approach was obvious. Under Martin O'Neill Sunderland used to be extremely passive defensively, dropping deep into two banks of four, seeking to frustrate opponents rather than actively disrupt their passing. Only Norwich, Stoke and Reading have averaged less possession this season; partly because there is a clear lack of guile in central midfield, but also because Sunderland so rarely regain possession close to the halfway line.
Here, they were considerably more energetic. Di Canio handed Connor Wickham, 20 last week, only his second league start of the campaign – the other was in the reverse fixture against Chelsea, coincidentally – and he covered long distances in the opening stages, putting David Luiz under pressure to prevent the Brazilian from starting attacks. Chelsea's midfield combination of Mikel John Obi and Ramires lacks invention, so the nullifying of David Luiz's attacking capabilities harmed Chelsea's ability to pass the ball forward.
Crucially, Wickham received great support from others. Stéphane Sessègnon, a dejected figure in recent months, charged forward to help close down Chelsea's defenders – the pressure created a half-chance within the first five minutes. The wide midfielders, Sebastian Larsson and Adam Johnson, also pushed up tight to the Chelsea full-backs.
Sometimes the closing down threatened to backfire – a couple of times Chelsea broke at speed once their defensive players had overcome the initial press, and Craig Gardner was fortunate not to be dismissed for a reckless lunge on Demba Ba when the Senegalese striker had dropped deep into his own half, starved of service further forward.
Nevertheless, against a Chelsea side physically and mentally drained by fixture congestion, a high-tempo game caused Rafael Benítez's side difficulties. You could predict Sunderland's gameplan without knowledge of Di Canio's tactics in his tenure at Swindon – this was a performance that perfectly reflected his personality, about fighting spirit and intensity, rather than organisation or discipline.
Sunderland's major problem was poor decision-making. Sessègnon shot wastefully wide when he should have squared to Wickham, then a brilliant counter-attack following a Chelsea set-piece ended with Johnson predictably cutting inside on to his left foot rather than taking the ball on the outside, allowing David Luiz back to block.
Still, when a scrappy own goal arrived just before half-time, it felt like Sunderland deserved a slice of luck for their sheer bravery.
It's difficult to tell precisely why Sunderland's approach changed so significantly after half-time. Perhaps the attackers naturally played with less ambition at 1-0 up, maybe Di Canio urged more caution in his half-time team talk, or it might have been an inevitable consequence of their exhausting first-half efforts. Whatever the reason, Di Canio's players retreated into their shells, inviting significant pressure – within 10 minutes they had conceded two goals, and Chelsea intelligently killed the remaining 35 minutes by keeping possession rather than chasing more goals.
In the early stages Sunderland looked like a Marcelo Bielsa side, then after the break they reverted to being a Martin O'Neill side. If Di Canio can replicate Sunderland's first-half performance they will escape relegation – but it will take a mammoth physical effort to sustain that level of pressure for long periods, especially once warmer temperatures finally reach these shores.