Lionel Messi was on target on that May night as they beat Manchester United 2-0 to add the Champions League to the La Liga and Copa del Rey trophies they had already pocketed earlier in the month. Gerard Pique, Sergio Busquets and Andres Iniesta also remain from the side that started in Rome that night. They were also part of the Barca side, six years later and under Luis Enrique, which won a second Treble.

Now, they're the spine of Valverde's Barca side, who are edging closer towards another season with the three biggest trophies on their radar. They begin Tuesday night's game in Rome with a 4-1 lead from the first leg and more than one foot planted in the semifinal for the first time since 2015.

Valverde noted on Monday that "extraordinary" things can happen in football but it would be really something if Roma could turn this around. For a start, they have to score three goals. To put the scale of that task into context: Barca have only conceded three goals in nine Champions League games this season.

Being on the fringes of another European semifinal, coupled with an 11-point cushion at the top of La Liga and a Copa del Rey final against Sevilla later this month, has led to giddiness in the Catalan press. "Ten reasons to believe in the treble," was one story on Diario Sport this week. And Jordi Alba says the "sensations" among the players are even better than in the season when, inspired by Messi, Luis Suarez and Neymar, they won it under Luis Enrique.

Obviously, no one's turning their nose up at a Treble, but it feels especially unique to Barca. It's one of the few things they have over Madrid, who have won it all time and time again but have never won it all in one season. Barca have done it twice. By the same reasoning, becoming the first side to go unbeaten through an entire top-flight season in Spain -- which, after 31 games, is still a possibility -- would have an added specialness.

Valverde, though, is not blowing any trumpets yet.

"What's better: winning the Champions League or going through the entire league season unbeaten?" he was asked last week.

"I've not done either of them so I couldn't possibly know," was his one line response.

What about the Treble, is that something that's come up in the dressing room?

"The only game we're focused on is the next one, against Roma," he said in his news conference on Tuesday, batting away the call to get carried away for the umpteenth time.

Instead, Valverde's asking his team to do the talking. On Saturday, as Barca matched La Liga's longest-ever unbeaten streak (38 games) by beating Leganes, he brought up 50 games in charge of the club. Since the back-to-back defeat to Madrid in the Spanish Super Cup, there has been just one defeat in 48 matches.

The numbers illustrate the strength of Valverde's side, too. While no other coach since the appointment of Johan Cruyff has lost fewer games (three) or conceded fewer goals (26) through 50 games, others have been stronger in other areas.

Luis Enrique, for example, won 42 of his first 50 matches, with his side scoring an incredible 143 goals. Valverde's side have won 36 games, scoring 116 goals. Pep Guardiola's and Gerardo Martino's sides both won more and scored more, too.

None of them, though, took on the job in the same circumstances as Valverde. Barca looked to have an ageing squad, signings were mocked, Neymar left and Madrid smashed them in the Super Cup. That they return to Rome this week, the scene of their first ever Treble, dreaming of a third is clear signal of just how well Valverde has navigated his first 50 games.

How he will ultimately be judged, though, as he regularly points out, now comes down to what Barca hope will be 12 final games: seven in the league, one in the Copa del Rey and a potential four, if they reach the final, in Europe.