The growing gulf in the Premiership, evident at Highbury on Tuesday, was again illustrated at Stamford Bridge last night as Chelsea were able to defeat Southampton despite fielding a near-reserve side in their Coca- Cola Cup fourth-round tie.

Once spurred into life by Kevin Davies' 50th-minute goal for Southampton, Chelsea largely controlled the game. An equaliser from Tore Andre Flo on the hour forced extra time then, with penalties three minutes away, Jody Morris earned Chelsea a quarter-final at Ipswich in the first week of January.

All three goals were well taken, but there should have been many more with chance after chance being spurned. Southampton's worst offenders were the least likely, David Hirst wasting two excellent early attempts and Matt Le Tissier passing up two clear, late chances. "We had the chances to win it," admitted David Jones, their manager.

Chelsea were little better but they did, at least, usually test the impressive Paul Jones. He was twice helped by Francis Benali who cleared off the line from Frank Sinclair and Mark Nicholls.

That Nicholls played in attack with Flo, while Mark Hughes was on the bench, said everything about Chelsea's approach on a night of contrasting priorities. Chelsea, with their minds on the championship and Europe, were not too worried about the Coca-Cola. Given that Southampton's priority, the avoidance of relegation, is probably more important than either of Chelsea's aims, one might expect them to do the same but, for their players and fans, the cup offered a prospect of light relief from the drudgery of the league. Their XI was at full strength.

Even with only two survivors from their last Premiership match, and a debutant in Nick Crittenden, Chelsea still had a formidable side. At its fulcrum was Ruud Gullit, nominally sweeper, who roamed Stamford Bridge's broad acres. Even he was regularly troubled by the promising Davies and it was no surprise when, five minutes into the second period, Davies ran on to Le Tissier's pass to score.

Gullit then departed and Flo levelled soon after, running on to Crittenden's pass and cutting inside Claus Lundekvam to score. A dozen chances later and it was into extra time. Hughes finally came on and, as penalties loomed, he took a pass from David Lee and laid it off to Morris who scored from 20 yards.

If Gullit looked unexcited it was because he had other things on his mind having become a father again on Tuesday. "It is so beautiful, so emotional, I was not tuned in tonight," he said. Unfortunately, for students of the football lineage, the English-born first offspring of Gullit and Estelle Cruyff is a girl, Joele.

Chelsea (3-5-2): Hitchock; Sinclair (Babayaro, 80), Gullit (Lee, 50), Clarke; Crittenden, Wise (M Hughes, 106), Lambourde, Morris, Granville; Flo, Nicholls.

Southampton (4-4-2): Jones; Dodd, Monkou, Lundekvam (Spedding 73), Benali; Le Tissier, Palmer, Richardson (Johansen, 93), Oakley; Hirst (Williams, 78), Davies.

Referee: D Elleray (Harrow).