It was surely with the mistaken belief that Chelsea's progress into the Champions League's last eight was a formality that Jose Mourinho taunted club owner Roman Abramovich with the words, "sack me and make me rich".

Because, for an uncomfortable period last night, Mourinho looked like getting his way. In the stands, the Russian oligarch watched unimpressed, his finger, itching, on the trigger.

Porto played a blinder. For a club that has never managed a win on English soil, coach Jesualdo Ferreira had injected belief into his side. In the Estadio do Dragoa, John Obi Mikel had thrown a fire blanket over Porto's winger Ricardo Quaresma, limiting his threat. Last night, Mourinho opted to deploy his own firebrand Arjen Robben, while Mikel watched from the bench. It was arguably a mistake as Quaresma sent Stamford Bridge into a spasm of anxiety with a 15th-minute opener.

Not until half-time, when Mourinho was able to calm some nerves and reinforce a strangely ineffective midfield with the appearance of Mikel, did Chelsea start to settle. Robben's long-range equaliser, three minutes after the restart helped, with Michael Ballack's clean strike sealing Porto's fate.

Chelsea Cech, Diarra (Ferreira 65), Essien, Carvalho, Ashley Cole, Makelele (Mikel 46), Robben, Ballack, Lampard, Shevchenko (Kalou 84), Drogba.
Subs: Hilario, Boulahrouz, Bridge, Wright-Phillips
Booked Robben, Diarra
FC Porto Helton, Fucile, Pepe, Bruno Alves, Cech (Ibson 55), Gonzalez, Ricardo Costa, Assuncao, Meireles (Adriano 55), Lopez (Bruno Moraes 82), Quaresma.
Subs: Vitor Baia, Alan, Postiga, Joao Paulo
Booked Quaresma, Fucile, Adriano
Referee R Rosetti (Italy)