The six-time Ballon d'Or winner has been a free agent since running his Blaugrana contract down at the end of last season, with negotiations ongoing to come to an agreement over an extension.
Barca are still said to be confident of getting Messi to commit his future to the club, but they have navigated their pre-season preparations without the Argentine while he is not under contract at Camp Nou.
Messi was recently pictured on holiday in Ibiza with former Barcelona teammate Luis Suarez, meaning that Ronald Koeman's side reported for training on Monday morning without the attacker present.
Barcelona are under pressure to offload several big earners before being able to tie Messi down to a new deal, but AS reports that the Catalan giants are determined to have the 34-year-old on the books in time for their La Liga opener with Real Sociedad on August 15.
Messi struck four goals and set up five more in seven Copa America matches for Argentina en route to the trophy, and he boasts 672 strikes from 778 games for Barcelona.
Monaco 
Stade Brestois 29 
Bordeaux 
Nimes 
Bayern Munich 
FC Augsburg 
Paris Saint Germain 
Toulouse 
CSKA Moscow 
FC Rostov 
Leicester 
Chelsea 
Valencia 
Betis 
Dynamo Kyiv 
Chornomorets Odesa 
Verona 
Inter 
Bayer Leverkusen 
FC Heidenheim 
Borussia Dortmund 
SC Freiburg 
VFL Wolfsburg 
Union Berlin 
Arsenal 
Nottingham Forest 
Everton 
Brentford 
Spartak Moscow 
Lokomotiv Moscow 
Rangers 
Dundee Utd 
Atletico Madrid 
Alaves 
Lens 
Marseille 
Ingulets Petrove 
Shakhtar Donetsk 
AC Milan 
Juventus 
ST Malo 
Manchester City 
Tottenham 
Eintracht Frankfurt 
Werder Bremen 
Girona 
Espanyol 
Feyenoord 
Heerenveen 
ST Etienne 
Montpellier 
Grenoble Foot 38 
Heart Of Midlothian 
Celtic 
Reims 
Lyon 
PSV 
Groningen