The Argentinian superstar scored a total of 60 goals and set up 28 more in 60 appearances last season, helping Barca capture a Primera Division, Champions League and Copa del Rey treble.
Messi, who came off the bench to score the winner in Saturday’s 2-1 triumph at Atletico Madrid that kept Barca perfect in La Liga and two points clear of Real Madrid at the top of the domestic standings, is expected to start against Roma.
“Messi is always the best on the pitch,” Barcelona forward Neymar said. “He always makes the difference and that helps us to win games.
“We’ve started the season well and we are working towards winning every game.
“It’s early days but we are on the right path.” Barca coach Luis Enrique is facing his former club, having been in charge of Roma in the 2011-12 campaign.
“It will be special because of how I was treated by the club and the players,” he said. “It’s a tricky and attractive group.
“We are the champions and we will try to make history by winning the Champions League in successive seasons.
“We did great last year but we all know that the past will not matter.” Roma were eliminated from Europe’s elite club competition last season in the group stages.
“We know it’s not going to be easy,” Roma winger Juan Manuel Iturbe said. “But it’s going to be a fantastic game.”
Elsewhere, Porto goalkeeper Iker Casillas will make a record-equalling 151st Champions League appearance when the Portuguese giants take on Dynamo Kiev in Ukraine tonight.
The 34-year-old, who left Real Madrid for the Dragoes this summer, will match the record number of appearances made by former Barcelona captain Xavi in the NSK Olimpiyskiy stadium.
Porto reached the quarter-finals last season before losing 7-4 on aggregate to Bayern Munich.
“The Champions League is a big aim for us and we hope we can have a good competition,” Casillas, who won the Champions League three times with Real, said.
“Let’s see if we can reach the final and play against Real Madrid.”