Gerardo Martino revealed he wanted midfield "control" after reaching the Copa del Rey final following Barcelona's 1-1 semi-final second-leg draw away to Real Sociedad.
Lionel Messi continued his return to form with the opening goal of the game on 26 minutes before his strike was cancelled out by Antoine Griezmann's second half stunner.
The result means the Blaugrana ran out 3-1 winners on aggregate and set up a clash with Real Madrid in the final, with Martino revealing his tactical tweak after the game.
He told reporters: "We wanted to play with more midfielders to have more possession, to have more control, so that Real couldn't impose their rhythm."
Xavi was substituted in the second half of Wednesday's game and Martino said his withdrawal was purely a precautionary measure.
"He had some discomfort and we didn't want to take risks," the Argentine added.
The Copa del Rey final will take place at Valencia's Mestalla stadium and could be held on Friday April 18, rather than Saturday 19, as a result of the Champions League semi-finals the following week.