Barcelona were clinical in front of goal while Liverpool were not. Two high quality sides played out the first leg of the Champions League semi-final at the Nou Camp.
The reds suffered an early injury to Naby Keita forcing a reshuffle after a strong start.
And for long periods of the game the reds looked confident and fluid and arguably playing the better football.
With Firmino only fit enough for a place on the bench, Klopp started with Wijnaldum in his place.
Joe Gomez returned to the starting line up in place of Trent Alexander-Arnold - his first start since the end of last year.
The reds started well, with Mane and Robertson in particular causing the Catalans problems.
But midway through the half Luis Suarez scored his first Champions League goal of the season when a great ball was whipped in by Jordi Alba.
Liverpool should have responded almost immediately - Jordan Henderson floating the ball through to Sadio Mane who put the ball over on a one on one with the keeper.
It set the tone for the game.
Barcelona enjoyed a brief spell of dominance after Naby Keita went off injured (Henderson on to replace him) but the reds slowly found their feet again and from the second half whistle upper their performance levels.
The reds saw most of the ball from the whistle.
Milner had a clutch of opportunities including one driving run after a great pass from Salah and dummy by Wijnaldum.
Barcelona were under the cosh and replaced Coutinho with a defender as they switched to a 4-4-2.
Their tactic of hitting the reds on the counter however led to the sucker punch when a ball bounced off Luis Suarez's thigh, on to the crossbar and rebounded perfectly for Messi to bundle over the line.
The Barcelona captain then scored his 600th goal for the Spanish side when he powered in a free kick from 30 yards into the tightest spot in the top corner of the goal. Unsaveable.
Liverpool are not the first and will not be the last to suffer at the hands of arguably the world's greatest footballer.
The reds couldn't get the vital away goal that would have really given them incentive for the second leg.
Barcelona have taken a huge step towards reaching the final. Liverpool need to draw on their reserves of the miraculous.