Messi, 33, moved past former teammate Xavi in Sunday's 1-1 draw in which the Argentine scored a first-half penalty. Messi's strike against relegation-threatened Cadiz also extended his La Liga record of scoring against the most different opponents to 38.
The Argentina forward is also closing in on Xavi's club record in all competitions. The former midfielder, now the coach of Al-Sadd in Qatar, made 767 appearances for Barca before leaving in 2015.
Messi played his 761st game for the Blaugrana in the league game against Cadiz and is on track to surpass ex-teammate Xavi in March.
However, Messi is still a long way short of the appearance record in La Liga. Goalkeeper Andoni Zubizarreta leads the way with 622 appearances in the Primera Division across spells with Athletic Bilbao, Barcelona and Valencia before retiring in 1998.
The Barca captain is a long way out in front as the league's top scorer, though. He has scored 459 times, with Cristiano Ronaldo second with 311 goals.
Paris Saint-Germain and Manchester City are the favourites to sign him if he does leave, although the Premier League club denied reports this week they have already offered him a contract.
Messi has been free to speak with other clubs since Jan. 1, when he moved into the final six months of his terms.