Aug 10 (Reuters) - Barcelona"s first European Cup winning side in 1992 was nicknamed the "Dream Team" yet no club deserves that moniker more now than Paris St Germain, who are poised to add Lionel Messi to their already star-studded squad. Messi, who gave a tear-soaked farewell press conference with Barcelona, is about to form a world-beating front three with former strike partner Neymar and France forward Kylian Mbappe. The trio could rival the unstoppable triumvirate Messi formed at Barca with Neymar and Luis Suarez for three seasons, scoring 364 goals and firing the team to a 2015 treble of La Liga, the Copa del Rey and Champions League. Yet that initial success was the start of a period of slow decline for Barca that should serve as a warning to PSG of the pitfalls of building a team stacked with talent yet short on work rate and ideas. Basing a team around three ferociously talented forwards eventually came at a cost to Barca"s overall balance and they soon found themselves unable to compete with the game"s top sides in crunch Champions League games. They were knocked out by Atletico Madrid the next season and lost 4-0 and 3-0 to PSG and Juventus respectively the following campaign. Neymar departed for Paris later in 2017 for a world record 222 million euros ($260 million) but Barca squandered their windfall on more pricey individuals such as Ousmane Dembele, Philippe Coutinho and Antoine Griezmann, while driving the club"s wage bill ever higher. La Liga titles still flowed but the team soon ceased to appear at the game"s vanguard. As the club became ever more in thrall to Messi, the continent"s other top sides continued to evolve, overtaking Barca tactically and physically. Stark warning signs were there, such as a 3-0 defeat to AS Roma in a 2018 quarter-final second leg and an even more crushing 4-0 loss to Liverpool the following season to lose a semi-final tie 4-3 on aggregate. The nadir came with a humiliating 8-2 defeat to Bayern Munich in the quarter-finals of the 2019-20 competition, while last season PSG ran riot at the Camp Nou in a 4-1 win eventually to condemn Barca to their earliest elimination in 14 years. Barca"s most painful loss, however, was the financial ruin that came with the coronavirus pandemic and which led them to accrue 1.2 billion euros in debt, leaving them unable to afford to keep Messi. The financial warning signs may also be there for PSG, who this summer signed Sergio Ramos, Georginio Wijnaldum and Gianluigi Donnarumma, all on free transfers yet all on huge salaries, in addition to splashing 60 million euros on Achraf Hakimi. PSG, however, have the luxury of being funded by the state-owned Qatar Sports Investment group. For now at least, PSG"s financial might may be unchecked but Messi"s arrival brings no guarantees they will win the Champions League title their owners crave. TALENTED INDIVIDUALS Questions will need to be answered about whether a squad with so many supremely talented individuals, several of whom are on the wrong side of 30, will be able to maintain a team ethos on the pitch. Coach Mauricio Pochettino will also have to show that he can exert his control on a star-studded squad, as predecessors Unai Emery and Thomas Tuchel struggled to do. While quieter than the likes of Ramos and Neymar, Messi has not always proven easy to manage. Former Barca coach Gerardo Martino said he knew Messi "could have got him sacked at any moment" while Quique Setien, who oversaw the traumatic defeat to Bayern, remarked: "He is very reserved, but he makes you see the things he wants." Pochettino has the advantage of hailing from the same part of Argentina as Messi and they share a passion for Rosario club Newell"s Old Boys. But he will have to tread a careful line between showing the player the respect his status demands without allowing him to become bigger than the club. ($1 = 0.8535 euros)