Captain fantastic scored the vital goal which dispatched dogged Middlesbrough and his all-round inspirational play drove on the champions to yet another victory.
With England midfielder Joe Cole suffering a strained left calf in training on Friday, it was the perfect opportunity for Jose Mourinho to re-introduce Arjen Robben to the flanks.
But it was Middlesbrough who had the first strike on goal on seven minutes. The chance fell to James Morrison, but his speculative long-range effort was easily held by home keeper Petr Cech.
Three minutes later and it was the Blues who attacked their opponents' area and they were unlucky not to score.
Damien Duff produced a mazy trademark run and his rasping shot, on target, was deflected from goal by Didier Drogba, who could not get out of the way.
Former Chelsea hitman Jimmy Floyd Hasselbaink proved just why he is still a favourite at Stamford Bridge. He always had an eye for goal and on 15 minutes found himself free in the penalty area.
Yakubu had his goalbound shot deflected by Terry into the path of Hasselbaink, but the Dutch striker's stretching right-footed shot clipped off the foot of Cech's left upright and away from danger.
A minute later and it was Robben who displayed one of his many adventurous runs.
Unfortunately for the winger, after drifting past three defenders, he had a rush of blood to the head and thrashed a right-footer well over Mark Schwarzer's crossbar.
Gareth Southgate managed to block first Frank Lampard and then William Gallas on 18 minutes.
Lampard then found himself on the edge of the penalty area following a flick by Drogba on 25 minutes, but the normally clinical midfielder could only see his blistering half-volley directed straight into the midriff of Schwarzer.
On 30 minutes Terry found a free header on goal but it was cleared off the line by Fabio Rochemback.
It took Chelsea until the 61st minute to make the breakthrough and Terry rose magnificently from a deep Duff corner to power down a header, on target. Rochemback could not stop the ball from creeping over the line.
Drogba missed a sitter, on 65 minutes, blasting over from ten yards following good byline work by substitute Shaun Wright-Phillips
A half-hearted shot by Yakubu ten minutes from time was Middlesbrough's final effort to nab a point, but Chelsea did enough to stifle any last-minute efforts and ran out deserved victors.
Man of the Match: John Terry - Proved to be Chelsea best prospect of a goal, especially from set-pieces, but from the defence he managed to coax excellent performances from Robben and Duff and that was enough to inspire the below-par champions to a vital victory.