The England international pairing, tormentors in chief of the Greeks, were Liverpool's goalscoring heroes, as their combination of power and movement proved too much for Olympiakos.
It was Heskey that opened the scoring in the 28th minute, beating the offside trap to latch onto Barmby's through ball to slip the ball underneath Dimitrios Eleftheropoulos and into the net.
Barmby's goal was frighteningly similar, this time Danny Murphy played him through in the 59th minute and the England international went around Eleftheropoulos before hitting a shot that sailed in off both posts.
The Greek side are notoriously poor travellers, having never advanced in any European competition on the basis of their away result, and after their poor display two weeks ago, it seemed they had lost their chance to beat the Merseyside giants.
Both sides started brightly but soon Liverpool were into their stride, the visitors having enjoyed a brief flurry which saw them win a dangerous free-kick which Pär Zetterberg took and was deflected over, the resulting corner was well cleared by the Liverpool defence.
Steven Gerrard was first to show for the home side as he saw his dipping volley brilliantly tipped over the bar by Eleftheropoulos in the fifth minute.
Heskey, currently in a rich vein of form went close two minutes later as he sidefooted over the bar after good work from Barmby.
However, the defensive frailities often shown by Liverpool this season could always come back to haunt them and they were lucky that Sami Hyppia and Sander Westerveld's miscommunication, did not allow Alexios Alexandris in as the ball was almost presented on a plate for the Greek striker.
In the main it was the home side doing all the pressurising and shots by Dietmar Hamann and Heskey gave Olympiakos food for thought.
The visitors were lucky to keep all 11 men on the field, when in the 32nd minute, Eleftheropoulos brought down Barmby who was clean through on goal, however, the referee felt lenient and the Olympiakos keeper escaped with a booking.
Four minutes later and Eleftheropoulos was quick off his line as Barmby and Heskey raced clear on the right, an untidy scramble where the keeper appeared to handle outside the area, ended with a throw in.
Olympiakos ended the first half with a brief flurry, however it was the home side that again dominated the second period. Hyppia saw his header cleared off the line by Grigorios Georgatos in the 55th minute as Liverpool piled forward.
After Barmby made it two-nil a succession of substitutions made the rest of the game more of a training exercise.
The Greeks will feel aggrieved that they were not given a way back into the match when in the 74th minute Predrag Djordjevic burst into the box and rounded Westerveld only to be brought down by the Dutch international.
To everyone's amazement, the Portuguese referee, Melo Pereira gave a goal kick. A black mark for Liverpool was an injury to Murphy who was replaced by Christian Ziege.
An unseemly ruckus between Ziege and Andreas Niniadis led to both being booked with five minutes to go but it was the home side that finished strongest and only Vladmir Smicier will know how he managed to blaze Barmby's low cross over the bar with the goal gaping.
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Click here to see the official Opta Stats from the game
