The Spaniard muscled his way into a two set lead and appeared set fair for victory when he went a break up in the third set against a player who had announced his imminent retirement from the circuit due to a persistent hip injury.
But with a straight sets annihilation looming, cussedness kicked in. Murray, the winner of three Grand Slam championships among his 45 titles, began to unfurl the attritional tennis that had so often befuddled the best players.
He retrieved the break and took the set in the tiebreak. The fourth set was collected in the same manner.
Pride regained. But that was the extent of the heroics. Bautista Agut was the fresher of their pair in the decider. After claiming it 6-2, his clenched fist and a scream of "Vamos" testified to the effort of dispatching even a crocked Murray.
"Honestly I've loved playing here over the years," said Murray after the match. "If this was my last match - an amazing way to end. I gave everything I had and it wasn't enough.
"Maybe I'll see you again," added the 31-year-old. "I'll do everything possible to try. If I want to go again I'll need to have a big operation which there's no guarantees I'll come back from. But I'll give it my best shot."
Bautista Agut, who beat world number one Novak Djokovic on his way to the Doha Open title in the prelude to the Australian Open, will face the unseeded Australian John Millman in the second round while Murray ponders his rehabilitation.
"Andy deserves this atmosphere," said Bautista Agut. "He gave everything until the last point. I want to congratulate him for all he did for tennis."
That encomium was the precursor to further tributes on the court's big screen.
Caroline Wozniacki and Sloane Stephens from the women's tour hailed him. Roger Federer, Djokovic and Rafael Nadal - Murray's adversaries in the so-called "Big Four" added their praises.
"I've been very fortunate - and unlucky - to compete in an era with all those great players around," Murray said. "To have the respect of your peers is a very special thing."