Ernesto Valverde wanted to keep Barcelona's feet on the ground after their 3-0 win over Liverpool so he hit his players where it hurt. "Liverpool are a team that can make any opponent suffer," he said in the press conference after the match. "And of course last year we had a three-goal advantage in the quarter-finals. And we were knocked out."
Valverde knows that loss to Roma still rankles with his players, barely a week passing without one of them referencing the game that defined their season last year and could yet shape this one too. The tie looked over after a 4-1 thrashing at Camp Nou only for a 3-0 loss in Rome to complete one of the great Champions League comebacks and send the Italians into the semis. That Real Madrid went on to win the tournament for a fourth time in five years rubbed salt into the wound.
"It is a thorn in our side," said Luis Suarez in September. But it was not just that Barca had fallen short, for a third consecutive year. It was the way they had thrown it away. "We feel like there is this scar," Clement Lenglet told AFP Sport in February.
"This match did us some harm. We want to erase that and have a beautiful season to forget it. We want to soothe the scar."
Thirteen months on, Liverpool will hope the doubt that lingers and, perhaps, the pressure to make amends can help them pull off what would surely be the club's most remarkable turnaround since the 2005 final in Istanbul.
"We have no reason to be complacent," Valverde said.
"The result is good, I have no doubt about that, but the tie is still open." Liverpool are stronger than Roma were. They have scored three or more goals 19 times this season, against opponents like Paris Saint-Germain, Manchester United, Arsenal and Porto. An early goal at Anfield on Tuesday and belief would surge.
But Barcelona are stronger too and another collapse, even against a team as dangerous as Liverpool, would be an even greater surprise.
When Roma left the first leg with a three-goal deficit, few could have predicted what would come next. But Barcelona had been stuttering for weeks, flattered by positive results that masked underwhelming performances.
Valverde's team are more convincing this season, almost faultless since February with 14 wins in 17 games, the two draws and a single defeat coming only after key players were rested.
Rotation means they are fresher too. Suarez has said he regrets playing three days before Roma against Leganes, as Valverde exhausted his team in pursuit of an unbeaten season in La Liga.
This year, Lionel Messi played just over half of the minutes he could have in April while against Celta on Saturday, Valverde rested all 11 players that started the first leg against Liverpool."We have the advantage of being champions already," Valverde said.
"Of course we will try to use it." Perhaps most importantly, last year's failure in the Champions League is what motivates Barcelona now more than ever.
Messi stood on the pitch at the start of the season and pledged to bring that "beautiful cup back to Camp Nou". He has played like a man on a mission ever since, with 12 goals in this season's competition already, two short of his best ever return in 2012. Messi's late double leaves Liverpool with a mountain to climb.
"The truth is we had a chance at the end and it would have been better to win 4-0 than 3-0," Messi said afterwards.
"It is a very good result but we are going to a very difficult stadium, with a lot of history, and that put you under a lot of pressure. We know it's not over."