Barcelona eased to another league title in the 2018-19 season, with Messi ending the campaign with 51 goals and 22 assists to top the charts in both areas.
Fabregas is now at Monaco, but played with the Argentine from the age of 12 before joining Arsenal at 16.
He would go on to return to Barcelona and line up alongside his old friend again in 2011 for three seasons - and the pair remain close to this day.
Messi has adapted his game as his career has progressed and Fabregas outlined why he still deserves the same level of plaudits, if not more, despite a reduced ability to take on players.
“That's the thing with Leo, he reinvents himself season after season,” Cesc said of the Rosario-born star. “Maybe he is not the player who dribbles past three, four or five players and score an outstanding goal any more.
“Instead, now, he prefers to do 50-yard passes, leaving Jordi Alba one-versus-one with the goalkeeper.
“He sees one-twos around the box, he might do a chip and an assist... I think now he is more complete than ever.”
At the end of season awards, Messi claimed the Pichichi award for a record-equalling sixth time.
His legendary status in football has long been confirmed but he may struggle to win the Ballon d'Or for his season after a disappointing Champions League exit at the hands of eventual winners Liverpool.
The Reds mounted an incredible 4-0 win at Anfield, coming back from a 3-0 defeat in the first league at Camp Nou. What followed was a 2-1 Copa del Reyfinal loss to Valencia, but Fabregas believes that Messi still deserves to be crowned the best player in the world.
“It is very difficult, it might depend on who won the Champions League,” Fabregas said of Messi potentially winning the Ballon d'Or.
“Normally, these trophies are appointed to people who win big things. I think Messi won it in 2010 when they only won the league so it is definitely doable.
“I think it is if it is all about who is the best, then Messi is the best. No doubt about it.
“I think Liverpool have had a fantastic season, though. Potentially one of their players could be on the podium, for sure.”
Messi does have one more stab at glory this term as Argentina compete in Copa America, starting with a clash against Colombia on Saturday.
Despite a wealth of attacking talent, however, the Albiceleste have rarely managed to live up to expectations at major tournaments in recent years.
Should Messi, the nation's captain, lead the country to glory at the umpteenth time of asking, then perhaps Fabregas will get his wish of seeing an old friend lift a record sixth Ballon d'Or.
