Despite perfecting the art of living all too dangerously at the back, Chelsea put the knock-out stages of the Champions League firmly within reach as they remained indebted to captain and talisman Dennis Wise against Marseille.

The Blues were worryingly vulnerable at the back, just as they had been last week in the 1-0 defeat to Marseille that left victory in the re-match against the French side at Stamford Bridge an absolute necessity.

But keeper Ed de Goey's goal this time survived intact even though Marseille rattled the post late on and forced the Dutchman into several top-class saves.

Yet, however narrowly in the end, the Blues had effectively won the game earlier on in central midfield, where Wise and fellow Englishman Jody Morris were outstanding.

And as Frank Leboeuf apparently aimed abuse at the Marseille fans at the end, the news came through that they had even risen from third to top of their roller-coaster group due to Feyenoord's goalless draw with Lazio.

As has all too often been the case this season though, chances came and went with alarming regularity by strikers Tore Andre Flo and Gianfranco Zola, who - apart from the 5-0 FA Cup romp against Gillingham - have not scored a single goal between them for two months.

So it was left to the inspirational figure of Wise to clinch victory with a 27th-minute strike, his third in the competition after an equally vital equaliser away to AC Milan in the first group stage and another goal against Galatasaray.

Wise, ably assisted by Morris was the heartbeat of the Chelsea, a figure of perpetual motion in central midfield as he again validated his recent call-up to the England starting line-up.

Chelsea boss Gianluca Vialli, who was back on the bench but, predictably, not as a substitute, had altered his tactics for the re-match, with a central midfield trio of Wise, Morris and Didier Deschamps, with Gus Poyet roaming at will.

While that midfield trio tackled and ran their hearts out, Poyet was relishing the extra freedom, firing an early low shot just wide and flicking on a corner towards Celestine Babayaro, whose close-range header was superbly saved by keeper Stephane Trevisan.

Chelsea still had to maintain their width yet Flo rose to the occasion, constantly pulling out wide to create space for his team-mates, and he soon crossed for Gianfranco Zola to see his shot blocked by Jean-Pierre Cyprien.

At the back, however, the Blues continued to appear as vulnerable as they had done last Wednesday in France, with Leboeuf looking especially unsure.

It was Leboeuf's slack clearance which conceded possession to dangerman Robert Pires and he fed Cyrille Pouget, who shot across goal before two quick breakaways led to Jerome Leroy and Ibrahima Bakayoko also threatening.

It was thrilling end-to-end football at this stage, even if the quality was somewhat lacking and neither side was keeping possession too well, but Chelsea made the most of their advantage when Wise struck.

Flo was again the creator, crossing for the diminutive Zola of all players to head the ball into the path of his onrushing captain, who finished with aplomb past Trevisan.

Sebastien Perez was injured in the build-up and soon had to be substituted yet Chelsea continued to press and Zola dispossessed Cyprien only to push the ball too far ahead of him.

Still Chelsea could not rest on their laurels though as their defensive problems continued, with Bakayoko's shot being saved by De Goey after Leboeuf had again been caught napping.

After Leroy's effort had been deflected wide by Albert Ferrer, Leboeuf then tangled with Bakayoko and after fouling the striker and producing an outrageous backwards dive when subsequently pushed, he was duly booked.

The Frenchman's ensuing sign to the bench was hardly complimentary about the Spanish referee but the official then did Chelsea a huge favour when he gave Deschamps a final warning instead of a second yellow card for a late foul on Leroy.

There was still time for Leboeuf, who was more impressive going forwards, to shoot at keeper Trevisan, and Babayaro to poke an effort wide after an almighty scramble in the penalty area.

But Chelsea just about deserved their half-time lead for their workrate if nothing else and they went in search of a second after the break only for Zola to find that for all his own endeavour, he has patently lost his touch in front of goal.

One shot went painfully wide, a trademark free-kick did come closer but a delightful shimmy ended with him falling flat on his backside.

Not that the game was over though, as was made all too evident by the way in which the Chelsea back four remained stationary as substitute Ivan De La Pena flicked the ball over them only for the advancing Jacques Abardonado to sky his volley over the bar.

Vialli was evidently attempting to hang on to the slender lead as he brought on Roberto di Matteo for Deschamps - after a display which was a slight improvement on last week's struggle - and defender Jon Harley for Zola.

Marseille simply threatened even more though in the last 10 minutes, with de la Pena rattling the post with an awesome 35-yard free-kick and de Goey saving superbly from Leroy.

It was backs-to-the-wall stuff from then on yet the final throw of the dice by the French was a shot by Bakayoko which was skewed wide from a superb position and Chelsea survived - just.

Vialli may have declared before the match that the Champions League is not as exciting as its previous format, the European Cup.

But perhaps this match was just a little too exciting - even if victory away to Feyenoord next week should now be enough to secure the Blues' quarter-final place.

Chelsea: De Goey, Ferrer, Leboeuf, Desailly, Babayaro, Morris, Deschamps (Di Matteo 79), Wise, Poyet, Flo, Zola (Harley 79).

Subs Not Used: Cudicini, Sutton, Ambrosetti, Lambourde, Thome.

Booked: Deschamps, Leboeuf.

Goals: Wise 27.

Marseille: Trevisan, Cyprien (De La Pena 66), Luccin, Abardonado, Perez (Fischer 38), Brando, Leroy, Dalmat, Pires, Bakayoko, Pouget.

Subs Not Used: Carasso, Martin, Keita, Martini, Moses.

Booked: Pouget, Fischer.

Att: 33,206

Ref: J Fernandez Marin (Spain).