An earth tremor lasting 30 seconds and registering 3.8 on the Richter scale was reported across the east Midlands yesterday afternoon. Chelsea were certainly shaken, although that was down to a rousing display from Derby rather than any geological phenomenon.

What Claudio Ranieri's half-time talk registered was not recorded but it had a galvanising effect. "I would not want to repeat it," admitted Mark Bosnich, the Chelsea goalkeeper.

The explosive nature of the afternoon continued long after the final whistle when Marcel Desailly and Fabrizio Ravanelli continued an on-field dispute that had earned each a yellow card. Having showered and changed, Ravanelli waited for Desailly outside the dressing-rooms some 30 minutes after the match. The two players were involved in heated exchanges in Italian and four stewards had to come between them.

His side's poor first-half performance prompted Ranieri to make his three substitutions at the start of the second half, bringing on Mario Stanic, Mikael Forssell and Frank Lampard.

Chelsea finally looked like a team that Colin Todd believes is capable of challenging for the Premiership title, although the Derby manager was not amused by comments that filtered out of Stamford Bridge before this game. Desailly and Boudewijn Zenden made dismissive remarks about Derby, with the Dutch midfielder claiming he had not heard of any of Todd's team.

Todd admitted he used those ill-advised remarks as a motivational tool. "We were disappointed with what they said," he insisted. "It was totally disrespectful to everyone at the football club."

Todd also defended his Italian striker: "Fab could have had a hat-trick. He has a lot of respect for this football club, and whatever problems he had at Middlesbrough he's been a model professional at this club."

Zenden will know more about Derby after this match which provided pulsating entertainment.

From the start, Todd's side made a mockery of their position near the foot of the table, and although there was more than a suspicion of offside about their goal, it was deserved.

Craig Burley played the ball low into the penalty area, Darryl Powell was denied by the first of several saves from the excellent Bosnich, and when Benito Carbone's follow-up squirted through to Ravanelli at the back post, the Italian easily dispatched his seventh goal of the season.

Derby could have had more and would have increased their lead if it had not been for Bosnich.

Burley, against one of his former clubs, played an incisive pass through the middle which sent Carbone darting through in the 22nd minute but the Australian goalkeeper made a superb double save.

Chelsea's best effort of an insipid first-half display came from a long-range effort from Mario Melchiot, but the defender was one of the three replaced during the break.

Although those changes had the desired effect, Chelsea would probably have lost but for another crucial intervention by Bosnich.

Deon Burton played a clever one-two with Ravanelli that set up the experienced striker for a shot that was destined for the bottom corner until Bosnich plunged to his left to save.

Chelsea swept upfield and within seconds were level. Ironically, it was Zenden who provided the cross that Derby failed to deal with and Forssell nipped the ball out to Jimmy Floyd Hasselbaink who lashed in his ninth of the season from just outside the box.

Suddenly, Chelsea were swarming all over Derby but they had a goalkeeper equal to Bosnich.

Mart Poom, back after a rib injury, somehow turned a Hasselbaink drive against a post and then picked himself up and flew to his right to claw away a 25-yard drive from Lampard.

As the play flowed from end to end, tempers began to fray with Desailly and Ravanelli involved in a heated exchange which ended with the Italian booked for pushing the French defender away.

Desailly was yellow-carded a minute later and Hasselbaink was also booked for dissent before each team almost stole the points in stoppage time. First Lampard slid the ball wide at the back post and then Ravanelli was once more thwarted by Bosnich from eight yards.

DERBY: Poom, Mawene, Higginbotham, Riggott, Zavagno, Ducrocq, Burley, Powell, Carbone, Burton (Christie 79), Ravanelli. Subs Not Used: Feuer, Boertien, Murray, Valakari. Booked: Ravanelli. Goals: Ravanelli 7.

CHELSEA: Bosnich, Gallas, Desailly, Terry, Le Saux, Melchiot (Stanic 45), Petit, Jokanovic (Lampard 45), Zenden, Hasselbaink, Zola (Forssell 47). Subs Not Used: Evans, Dalla Bona. Booked: Petit, Gallas, Desailly, Hasselbaink. Goals: Hasselbaink 48.

Referee: S Bennett (Kent).