It was widely predicted and proved simply unavoidable, but another defeat in the Nou Camp was no less painful for Celtic on their return to Champions League group stage football.
Crushed 6-1 at the same venue in their last fixture at this level three years ago, they were comprehensively outclassed again as this proved an assignment beyond even the revitalising effect Brendan Rodgers has had on the Scottish champions.
The gulf in standard between the domestic environment, where Celtic are so dominant, and Europe’s elite competition no longer needs to be underlined for anyone who has been paying attention in recent years.
But this loss, the heaviest Celtic have ever suffered in their 54-year history of European football, serves as a sobering, if unsurprising, reminder.
On a night of little consolation for Rodgers’ side, for whom even a missed penalty by Moussa Dembele when the score was still only 1-0 could scarcely be regarded as a game-changer, they can at least reflect with complete certainty that they were taken apart by one of the best teams ever to play the game.
Lionel Messi led the charge with a hat-trick, Luis Suarez grabbed a double, while Neymar and half-time substitute Andres Iniesta weighed in with one each. It was an attacking masterclass on a grand scale.
As is the case for any side travelling to the Nou Camp, the possession statistics which are habitually and heavily in Barcelona’s favour presented one of the biggest challenges for the visitors.
But there was another number which Celtic had to cope with on this occasion, a stifling 67 per cent humidity at the end of a day when the city had been smothered in temperatures in excess of 30 degrees.
For such a punishing shift, Rodgers opted for a five-man defence in which Cristian Gamboa was handed his debut for Celtic in the most demanding circumstances imaginable. The Costa Rican international slotted in at right-back as Mikael Lustig joined Kolo Toure and Erik Sviatchenko in a three-man central defence book-ended by left-back Kieran Tierney.
One of Gamboa’s first touches in a green and white hooped shirt was a telling one as he managed to nick the ball off the toes of Suarez in the second minute, just as the striker was about to connect with the first of many brilliantly precise passes Messi made on the night.
But Rodgers’ hopes of frustrating Barcelona for the opening half hour or so, which he had outlined on the eve of the match, lasted barely another 60 seconds as Celtic’s failure to defend the subsequent corner saw them fall behind.
The visitors were caught a little flat-footed as Neymar played it short from the left. The Brazilian worked a position on the edge of the penalty area from where his sublime reverse pass picked out Messi’s run between Gamboa and Lustig. Celtic goalkeeper Dorus de Vries had no answer to the little Argentine’s rasping left-foot shot high into the net.
It was the most ominous start possible from Celtic’s perspective. With Barcelona’s celebrated front three of Messi, Suarez and Neymar all in the starting line-up for the first time this season, the Spanish champions were clearly in the mood to deliver a performance full of their trademark fluency and incision.
Messi curled a shot just wide of De Vries’ right-hand post, then Suarez narrowly failed to connect cleanly at the back post with a Messi cross from the right. Celtic were barely able to cross the halfway line until, out of the blue, they sourced a glorious opportunity to equalise in the 24th minute.
Scott Sinclair cut in from the left to embark on a terrific run through the middle which suddenly had the Barcelona defence back-pedalling uncertainly. Sinclair slipped a clever pass to Dembele who was brought down by Marc-Andre ter Stegen as he tried to round him just outside the six-yard box.
It was a clear penalty kick and yellow card for Ter Stegen, despite the vehement protests from the German keeper. But his mood was soon much brighter as he dived to his right to save a less than convincingly struck spot-kick by Dembele.
The young French striker’s failure to repeat the cool and crucial finish from 12 yards with which he had helped Celtic defeat Astana in the qualifying rounds was quickly punished by Barcelona who doubled their lead three minutes later.
It was a brilliantly crafted goal, with a couple of one-twos executed with bewildering speed and accuracy between Neymar and Messi. With the Celtic defence carved apart, Messi was left with a simple close-range tap-in.
Suddenly, Celtic were on the rack and it was something of a feat in itself that they managed to avoid sustaining any further damage on the scoreboard before half-time. Suarez saw a clever chipped effort drift narrowly wide, then midfielder Andre Gomes had a close-range shot blocked by some desperate Celtic defending.
It was relentless stuff by Barca now. Tierney did well to clear Ivan Rakitic’s effort off the line, then De Vries made a smart save to deny Neymar.
The dam burst in the second half, however, as it turned into the rout which was always on the cards. Neymar made it 3-0 with a sweetly-struck free-kick which De Vries, despite getting a hand to the ball, could not keep out.
Iniesta, whose appearance for Rakitic at the break summed up the depth of Barca’s talent, thumped home number four with a right-foot volley from Neymar’s pass, before Messi completed his hat-trick on the hour with a tap-in from a Suarez cross.
The only thing missing from an otherwise complete Barcelona display was a goal by Suarez. It duly arrived in the 75th minute when he controlled a Neymar pass on his chest before swivelling and smashing home a left-foot volley.
The agony wasn’t over yet for Celtic, Suarez helping himself to another with two minutes remaining as he converted a Messi cross from close range. The final whistle was nothing less than an act of mercy for the bemused visitors.
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