Celtic 1 Barcelona 0
By Graeme Bailey
Last Updated: 01/01/70 1:00am
An Alan Thompson strike on the hour proved the difference between the two sides, but Barca will be left rueing a string of missed chances.
The first half somehow finished goalless, with both sides missing opportunities - although it was the Spaniards who had the better of them.
After just five minutes, Ronaldinho gave the home fans a sign of what was to come as a his clever turn and pass found Javier Saviola eight yards out - but he fired wide.
Martin O'Neill's men then came into the game and went close through Stephen Pearson, who lashed his 25-yard effort into the side netting.
Barca captain Phillipe Cocu then lashed wide, before again Ronaldinho - aided by Xavi Hernandez - opened up the Celtic defence with ease - but again Saviola blasted wide when well placed.
Bobo Balde then found himself in an unaccustomed attacking role, but he did well to get a shot off when pressured by Michael Reiziger and he forced young keeper Victor Valdes into a save.
Ronaldinho then had a wonderful chance to open the scoring after Saviola put him through on goal, but the Brazilian lashed his shot wide with only Rab Douglas to beat.
The Samba maestro then produced another moment of magic when he spun the ball away from Didier Agathe, before skipping past him and finding Luis Garcia in the six-yard box - but he could not re-direct the ball towards goal.
Thompson then had Celtic's best chance of the first half, but his right footed effort was easily palmed away by Valdes.
The game then irrupted, but not on the pitch - in the tunnel as Thiago Motta and Douglas clashed and both received red cards from non-nonsense German official Wolfgang Stark.
Barca began the second period where they left off and Ronaldinho again created a goalscoring chance for his side, this time with a brilliant 40-yard ball over the top of the Celtic backline - but Saviola again could only fire past the post after beating replacement keeper David Marshall.
The game then turned in Celtic's favour when Saviola petulantly kicked out at Thompson and Stark immediately gave him his marching orders.
As far as Barca were concerned, that was it for them and Celtic to their immense credit took over proceedings and it was no surprise when they went ahead.
The goal came when Stilian Petrov crossed from the right and for the first time in the game, Henrik Larsson escaped the attentions of the excellent Carles Puyol to head down for Thompson - who lashed the ball home from close range.
With the extra man, Larsson was now getting more room and he should have doubled Celtic's lead with just 15 minutes left when Pearson nodded the ball into his path, but the ubiquitous Swede could only pull his shot wide.
Celtic again proved that they really have what it takes to mix it with the best in Europe and they will travel to Camp Nou later this month full of confidence for the second leg.