Andy Murray has rubbished talk of a rift with coach Amelie Mauresmo after he crashed out of the Miami Open with a three-set loss to Grigor Dimitrov.

Mauresmo watched on from a different part of the stadium to the box where the rest of Murray's team and family were located as the world number two produced more than 50 unforced errors in a 6-7 (7/1) 6-4 6-3 loss to the Bulgarian.

Murray, who received a violation from the umpire for smashing his racket during the second set, insisted that Mauresmo was sat elsewhere in a bid to curb his on-court tantrums.

"I've just been trying to find different ways to improve my focus on the court," Murray said in his post-match press conference reported by the Daily Mail. "I also did the same thing at the O2 Arena as well, so I'm trying to find different ways to improve and that's something I've tested to see if that might help.

"If I'd had a falling out then Amelie wouldn't be here at the tournament. We had dinner with all our families last night, so we certainly haven't fallen out.

"It's one of those things that when I win no one says anything about it, and then when I lose that's an excuse. I don't think that is the reason for me hitting 50 unforced errors in this match."

The defeat, in which Dimitrov showed the sort of form which propelled him into the top 10 of the world rankings in 2014, brought to an end a difficult American hard-court swing of the season for Murray, who is still facing challenges of life as a new parent.

He lost to Federico Delbonis at the BNP Paribas Open in Indian Wells a fortnight ago and he has won just two ATP World Tour matches since the final of the Australian Open in January.

While Murray has regularly complained of the alien conditions in California, Miami is a home away from home as the Crandon Park complex serves as his training base for three months of the year and he has won the title there twice - in 2009 and 2013.

After Murray won the first set on a tie-break Dimitrov hit back by winning the first four games of the second set - a sequence which led to Murray getting violent with his racket.

The Bulgarian held off a brief fightback to take the set 6-4 before Murray put himself in pole position to book a quarter-final spot by breaking to lead 3-1 in the decider.

But a capitulation from the Scot, who cut a disconsolate figure in the latter stages of the match, saw Dimitrov win five games in a row.

"It's very disappointing because I had plenty of time to prepare and practice for this," said of the conditions in Miami.

"I got myself in a winning position so it couldn't have been that bad, but couldn't close it out. There were far too many unforced errors that crept in towards the end.

"Grigor is obviously a very good player, but I also had opportunities in this match. I was up a break in the third, same at Indian Wells, then lost a run of games in both matches. So I need to look at that and see where I go from there."

Trailing 3-1 in the final set Dimitrov could easily have crumbled and allowed Murray through, but the Bulgarian was confident he would turn his fortunes around.

"Coming into the third set I knew Andy was going to run down every shot and he was up a break," he told Sky Sports 3.

"That didn't discourage me but I felt I was striking the ball well and I thought I would get a chance and I saw that opportunity and I was on top of my game when it came. Physically I felt fine and so it is on to the next one.

"I have been working a lot, my main goal was to leave myself on the court and that is what I did. I took my opportunities, my break point percentage was high and that gave me a pretty comfortable advantage."