The Catalans toiled in the Argentine's injury-enforced absence and only sealed victory in the latter stages after Bhoys skipper Scott Brown had been sent off for a kick on Neymar.
The Argentine attacker limped off just short of the half-hour mark as Barca beat Almeria 2-0 in La Liga on Saturday and will be sidelined for around two to three weeks, the Camp Nou outfit later revealed.
"For any team in the world it would be difficult to replace Messi," coach Gerardo Martino told reporters ahead of Tuesday's game. Sporting director Andoni Zibizarreta, however, was more upbeat. "We will cope without him," the Basque predicted. And the club did - just about.
Like last season, Barca had the better of the game and the greater share of the possession at Parkhead, but the Catalans again found it difficult to break down the Scottish side and only made the breakthrough after Celtic captain Scott Brown was dismissed for kicking out at Neymar in the second half.
|BARCA WITHOUT MESSI IN CL (2013)
Cesc's intervention settled it, however. "It was a deserved victory," the midfielder said straight after the final whistle. "I believe it was our most complete match this season."
Coach Martino was in agreement.
"It was probably the most complete match we have played," he reiterated. "We controlled it, combining direct play with large spells of possession, and we didn't give away many chances."
Prior to Brown's dismissal, however, Barca never truly looked like scoring and the Catalans still seem somewhat toothless when their star man is missing. So even though the result was right in the end, 'Tata' will hope Neymar can continue to grow and fill the Argentine's sizable shoes if he is absent later on in the competition.
That will be when the true tests arrive and, as former Real Madrid boss Jose Mourinho told Andres Iniesta last season as he hit back from criticism over his treatment of Iker Casillas, Barca simply is not the same side when Leo is out.
"Iniesta can say what he likes, but I would say to him that without Messi his team is so different and that is why they did what they did in the Champions League (when the Catalans lost 7-0 on aggregate to Bayern Munich in the semifinals last season)," the Portuguese manager said.
Pep Guardiola always admitted it, too. "Without Leo we would be a very good team and we would be competitive, but we wouldn't have been able to achieve all that we have if he were not here with us," the Catalan coach once admitted.
If there is one criticism of Guardiola in his ultra-successful spell at Camp Nou, it is that he did not devise a plan for those rare occasions when Messi was kept quiet or looked off color, as against Inter and Chelsea in the Champions League semifinals of 2010 and 2012, respectively.
Guardiola was fortunate, however, in that during his tenure Messi was virtually ever present - his injury problems confined to the past. But Leo's fitness worries have since returned and Martino must now solve a puzzle Pep never really had to and one which Tito Vilanova was unable to figure out: how to make Barca brilliant even when Messi is not around. With the Argentine increasingly injured in recent months, the Catalans' Champions League hopes may just depend on it.
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