Xavi was speaking after their 1-0 win over Atletico Madrid in LaLiga on Sunday.
The result saw Barca go 11 points clear of second-placed Real Madrid on the table with eight fixtures left.
Ter Stegen also equalled Claudio Bravo’s clean-sheet record of 23 games in a single LaLiga season.
“Marc André ter-Stegen is among the three best goalkeepers in the world and because of our game I think he is the best,” Xavi said after the game.
Barcelona are away at Rayo Vallecano next on Wednesday, April 26.