They are only four games from an unbeaten La Liga season.
This is Barcelona's 25th La Liga title.
I'm delighted because this has been a very long competition that we have been chasing since the moment we went to the top of the table.
The 24-year-old is expected to seal a permanent deal to the Premier League side this summer after impressing.
After conceding, Ernesto Valverde's men attempted to take the sting out of any further Branquiazuis comeback by controlling possession at a pedestrian pace; which they did with great effect until referee Bengoetxea brought an end to an action-packed first half.
Messi saw a 30-yard free-kick expertly saved by Ruben Martinez before desperate Depor twice went close, first Borja Valle failed to make clean contact with Michael Krohn-Dehli's teasing cross before Fabian Schar inexplicably headed over from six yards.
"We are playing nearly a final tomorrow and we want our fans to be with us and carry us to a win". "We were better than our rivals". I have tried to make sure that the team sticks together, especially through the more hard times. "It's more of them than the coach", he said.
Denis Suarez made a big impact off the bench and was involved in the final two goals.
"[The double] has only been done eight times in Barcelona's history and we have to be very happy".
Barcelona is celebrating yet another Spanish league title to cap a almost ideal season.
Despite claiming the league title, Valverde was sad to see the contrasting emotions between the two sides at the end of the game, as Barca celebrated and Deportivo came to terms with their relegation. "Winning seven league titles out of the last ten is outrageous and just look at how we did it this year, with four games remaining".