Blackburn Rovers 0 Celtic 2 (agg 0-3)
Celtic tonight proved, if proof was needed, what a valuable addition they would be to England's top flight.
Up against a side lying seventh in the Premiership and on their own patch, Martin O'Neill's side gave a performance that smacked of class and authority.
One goal to the good from the first leg thanks to Henrik Larsson, they secured their passage into the third round of the UEFA Cup courtesy of another goal from the Swede and a header from former Blackburn striker Chris Sutton.
Larsson took his tally to 21 for the season in front of over 8,000 Celtic fans, when he capitalised on some slack defending to find himself confronted with the onrushing Brad Friedel.
Having looked like he had pushed it too far the striker calmly lifted it over the American to leave Blackburn needing three.
Moments beforehand Andy Cole almost opened the scoring after a neat through ball from John Curtis but he could only get the slightest of touches and goalkeeper Robert Douglas was able to clear.
Celtic were not content to sit on their lead however and Petrov saw a shot go inches wide of the post following a short free-kick from Larsson.
Souness made a switch at half-time, bringing on Keith Gillespie for Curtis in the hope he could unlock the Celtic defence.
However it was Celtic who began the second half with a bang when Larsson knocked a fierce shot wide.
It should have been game over in the 49th minute when Larsson played the ball in but first Sutton and then Hartson failed to convert the chance with the goal at their mercy.
There was another moment of danger for Blackburn when Guppy whipped in a cross from the left that Friedel was glad to tip over.
The home side were beginning to run out of time and Cole was wasteful when he latched on to a ball from Gillespie.
Souness then decided to switch things around up front bringing off the ineffective Dwight Yorke for Matt Jansen in the 64th minute, but it was the visitors who went 2-0 ahead on the night and 3-0 on aggregate in the 67th minute.
Sutton peeled away from his marker and got on the end of Petrov's corner to head home at the near post on his return to his former club.
O'Neill freshened things up in the 77th minute when he replaced the tiring Petrov with Alan Thompson.
Thompson whipped in a low cross for the home side with a minute to go but Ulrik Larsson scrambled the ball away.
Blackburn were desperate for a consolation goal but Celtic held firm for a famous victory.