Barcelona dominated possession, hit the bar and the post and had what looked like a certain goal cleared off the line at a rain-lashed Stamford Bridge.
The Spaniards had 24 attempts on target compared to one by the hosts but Ivorian Drogba made the most of his sight of goal when he fired low and hard past Barca goalkeeper Victor Valdes two minutes into stoppage time at the end of the first half.
"We created so many chances, I had no idea we were going to do that, but we failed to score against a very good side who were very strong," Barcelona manager Pep Guardiola told a news conference.
"You have to be a strong side to be in the semi-finals of the Champions League. We knew it was going to be a tough challenge and it was."
Lampard's raking pass found Brazilian Ramires whose low cross from the left eluded the Barca defenders with Drogba pouncing at the far post to score.
Di Matteo was full of praise for Chelsea's "old guard", who followed up last weekend's 5-1 thrashing of Tottenham Hotspur in the FA Cup semi-finals.
"In the past a lot public opinion said that these boys, the old guard, are over the line and too old to play two games; they have played two games in a short period of time, and I think they gave the answer on the pitch tonight."
The defeat was only Barcelona's third loss in 63 games this season and they have now failed to beat Chelsea in the last six matches against them and the Londoners are now unbeaten in 14 matches, home and away against Spanish opposition.
But that tactic did pay dividends for the goal - just after Barcelona had fluffed another good scoring chance four minutes earlier when Messi went on a jinking run through the Chelsea defence before teeing up Cesc Fabregas with a shot that looked goalbound until Fabregas's former Arsenal team-mate Ashley Cole cleared the ball off the line.
