John Terry might have relished the home comfort. Back at the stadium in which he is feted as a captain, leader and legend, the player who has come to epitomise the modern Chelsea felt only love from the stands. In light of his trial for allegedly abusing Anton Ferdinand in racist terms – for which he was found not guilty – he must develop an even thicker skin than usual for away trips. He received dog's abuse from Manchester City's supporters during the Community Shield and he was even booed a little at Wigan Athletic on Sunday.

The homecoming, though, was undermined by a looseness at the back that might have Terry and his colleagues squirming when they are forced to sit through the rerun at the training ground. There was deserved victory late on, even if there was fortune about Fernando Torres' vital third goal, when the assistant referee erred, to Reading's disgust, on an offside decision. But Terry and his self-critical colleagues will know that they cannot offer the foundation for a Premier League title challenge on this defensive form.

Much has been made of the new-look Chelsea, a squad studded with fantasy attacking signings and, for the opening 25 minutes and spells of the second-half, it was easy to sit back and enjoy.

Juan Mata sparkled, Eden Hazard was tremendous and even Mikel John Obi surged forward. But, in what felt like the blink of an eye, newly promoted Reading managed to turn the game on its head, with two goals in four first-half minutes. And if it was easy to detect a lack of concentration or a touch of complacency about Chelsea's defending, the harsher view pointed towards a vulnerability.

Chelsea's defending was the basis of their glorious finale to last season but on Wednesday night it was like watching imposters at times. Gary Cahill was a bystander as Pavel Pogrebnyak thumped home the Reading equaliser and Petr Cech guaranteed himself entrance to the goalkeeping blooper reel after his comically miscued attempt to hack clear Danny Guthrie's free-kick.

Terry had been culpable for the award after he was out-stripped by Jobi McAnuff; the captain's game was not of the legendary variety.

It was not only the goals conceded. Reading flickered on the counterattack and they almost staged the grandstand finish while they would have led 3-1 at the interval had Alex Pearce got more on a free header after waltzing through to meet Ian Harte's free-kick.

The Chelsea manager, Roberto Di Matteo, spoke of a "loss of composure" for the Reading goals and he admitted that as Chelsea chased the game at 2-1 down, "we were very offensive and maybe lost our balance a bit".

He was left relieved when Hazard streaked away to lay on the clinching fourth goal for Branislav Ivanovic and the Italian in Di Matteo might simply have pined for greater security. He is not beloved of shootouts, unless they take place from 12 yards and deliver Europe's most glittering trophy, and his biggest test is to balance the old and miserly Chelsea with the exciting new one.

"The balance was always going to be the key," Di Matteo said. "It's all great and everyone wants to see a lot of flair play but to win games, you need a good balance to it. That's going to be the challenge."

It was also the night when Stamford Bridge welcomed the European Champions for the first time and evidence of the triumph was everywhere, from the slogans on the fans' T-shirts to Terry's programme notes, where he paid a warm tribute to the departed Munich match-winner, Didier Drogba.

Reading, though, went close to spoiling the party and their supporters will never forget the richest of first-half seams when they forgot the shadows that they had chased to fashion an explosive combination punch. This time last year, Brian McDermott's team were recovering from a 2-1 home defeat to Barnsley in the Championship but here they sat, for the best part of 40 minutes, on top of the Premier League.

Garath McCleary caught the eye on the right, just as the thrusting McAnuff did on the left, and it was one of McCleary's driven centres that ushered in Pogrebnyak for his headed goal. The Russia striker showcased his battering-ram style in the second-half of last season at Fulham and his first goal in Reading colours took the breath. He is made for the Premier League.

The Blues pushed throughout the second-half yet the unease at the back bubbled when Terry battered an attempted clearance against Ashley Cole and out for a corner.

Chelsea could be indebted to the Reading goalkeeper, Adam Federici, for his bid to out-do Cech in the flapping stakes for Cahill's equaliser and the home crowd went home happy.

They will be happier when Terry and Co locate their ruthlessness.