Murray reached the last-32 at the BNP Paribas Open last week but conditions in Indian Wells differ slightly to Miami, even if the former world number one felt he had been practising well in recent days.
The 35-year-old Scot, who won this event in 2009 and 2013, felt restricted throughout and delivered an off-colour showing as he crashed to a 6-4 7-5 defeat to his Serbian opponent, ranked 76th in the world.
“It’s a very different court here, very bouncy and much faster than last week,” Murray, currently 52nd in the world, said afterwards. “It was very different to the practice courts and everything.
“I served pretty well but the rest of the game was a bit of a problem. My timing was off a bit, the ball was obviously bouncing up a bit higher and I just mistimed quite a few balls.
“I struggled a bit with my movement, I’m not quite sure why that was. But I wasn’t expecting to play like that, even based on the last few days because I’ve been decent in practice.”
Murray, who revealed he struggled with fatigue during his third-round defeat to fellow Briton Jack Draper in Indian Wells, will now begin building towards the upcoming clay season.
“I’m going to Spain,” he said. “My family are going there on the 30th, so I’ll join them. We’re going to do some training in the south of Spain for a week or so. I’m not sure what I will do before then.
I wasn't expecting to play like that, even based on the last few days because I've been decent in practice
“I was hoping to do much better here. So whether I stay and train here on the clay for a few days before heading to Spain, I’m not sure.”
While Murray’s Sunshine Swing is over, Carlos Alcaraz will be looking to do the double in the next fortnight. The Spaniard, the defending champion in Miami, lifted the Indian Wells title last weekend.
Back at the top of the world rankings, much is expected of the 19-year-old as the era of unprecedented dominance led by Roger Federer, Rafael Nadal, Novak Djokovic and, at times, Murray himself winds down.
Murray feels Alcaraz can live up to the hype but warned against placing too much expectation on the teenager’s shoulders.
“He has an excellent, all-around game that I think will translate well on to all surfaces,” Murray added.
“He’s so far in his young career doing better than most of the guys that have come (through in) the last eight to 10 years. I know a lot of people are expecting everyone to win 20-plus grand slams now, like that’s normal. I wouldn’t predict that for anyone.
“I would imagine he would be right at the top of the game for as long as he wants to play.”
On a day of exits for British players in Miami – following Emma Raducanu’s earlier defeat – Kyle Edmund also lost.
The former British number one, who missed most of the last two seasons because of a chronic left knee problem has required three operations, suffered a 7-5 7-5 defeat to China’s Wu Yibing in one hour and 35 minutes.