The Argentinian missed Barca's opening game of the 2019-20 La Liga season last Friday when the defending champions lost 1-0 at Athletic Bilbao.
The Blaugrana will be aiming to get their first win of the new campaign at the Camp Nou against Betis, and their chances will be boosted if Messi is involved.
According to Sport's Jordi Gil, the 32-year-old is "fully recovered" from his injury and will join the rest of Barca's squad in training on Friday and Saturday before a decision is made about his involvement against Betis.
Gil added, barring any setbacks, Messi could be included in Barca's starting XI on Sunday, but he is "extremely unlikely" to play 90 minutes.
OTRO provided footage of Messi training on his own as he aims to get back to 100 per cent fitness:
The five-time Ballon d'Or winner remains Barca's most important player.
He netted 36 goals in 34 appearances last season as Barcelona won the La Liga title by 11 points.
Defeat on the opening day of the new campaign was an inauspicious way for Ernesto Valverde's side to begin their title defence, and their toothlessness in front of goal was a surprise given they scored 90 times in the league last term.
The return of Messi would go a long way to solving any goalscoring issues Barca may have because he brings other players into the game and scores consistently himself.
The last time Barcelona met Betis back in March, Messi netted a hat-trick in a 4-1 victory at the Benito Villamarin Stadium.
However, in the reverse fixture at the Camp Nou in November, Barca suffered a shock 4-3 defeat.
They will be desperate to avoid the same result on Sunday, and if Messi is available to play, Barca will be strong favourites to pick up three points.