Barcelona coach Luis Enrique and defender Jordi Alba hailed "incomparable" Lionel Messi as the Spanish league giants look to take the first step towards the defence of their Champions League crown against Roma on Wednesday.

Barcelona, 3-1 winners over Juventus in last May's final, are being tipped to become the first team since AC Milan in 1990 to successfully defend their crown.

Roma's Stadio Olimpico is expected to host a sell-out crowd of 72,000 for the Group E encounter -- a rare occurrence, but one which illustrates the attraction of one of the world's best football sides, and one of the game's greatest players.

It will be Messi's 100th Champions League appearance and for Enrique, Messi beats them all.

"You know my opinion (on Messi), but I can give it to you again," Enrique, who coached Roma for a rather fruitless season in 2011-2012, told media in Rome on Tuesday.

"Messi isn't just the best player in the world, he's the best the game has ever seen."

Alba, when asked to compare the Argentinian with Real Madrid striker Cristiano Ronaldo, said the Argentinian wins hands down.

Prior to Real's home game against Shakhtar Donetsk on Tuesday, both Messi and Ronaldo had scored a record 77 goals in the competition.

"Ronaldo is a great goalscorer, but what Leo does on the pitch, no one else does. It's incomparable," said Alba.

"When you have Leo on the pitch, everything changes. For me, he's five steps ahead of everyone else."

Given Barcelona's status as favourites, Roma host the defending champions with the prime objective of limiting the damage less than a year after a humbling 7-1 defeat to Bayern Munich drastically compromised their group stage qualification chances.

Giallorossi coach Rudi Garcia insisted earlier they won't be going out to specifically stop Messi from wowing the Stadio Olimpco.

"We don't have an anti-Messi plan, just as there isn't one to stop (Luis) Suarez or (Andres) Iniesta," Garcia said.

"As (midfielder) Daniele De Rossi has said, you deal with the threat collectively, both in attack and defence."

Enrique said he has few remarkable souvenirs of his spell as Roma coach: "It was too long ago."

But the Spaniard expects Garcia's men to produce the kind of battling performance that resulted in a 2-1 win over last season's beaten finalists Juventus in Serie A a fortnight ago.

"I expect Roma to be similar to the team that beat Juve. They will put us under pressure, try to keep possession and they will have chances to score," added Enrique.

While Roma's defence has yet to settle following the recent arrival of Antonio Rudiger and Lucas Digne, Barcelona's well-drilled back four welcomes the return of Gerard Pique from a three-match La Liga suspension.

For Alba, the timing couldn't be better: "We have confidence in all our central defenders, but Pique is a leader both on and off the pitch.

"He's one of the best in the world in his position and gives us a lot of guarantees."
Source: AFP