Andy Murray missed a match point and blew a 5-2 lead in the final set to suffer his sixth straight defeat to Alex de Minaur in the Paris Masters first round on Tuesday (AEDT).

The three-time Grand Slam champion appeared poised to finally clinch a first win over Australian De Minaur after a double-break in the deciding set, but slumped to a 7-6 (7/5), 4-6, 7-5 loss.

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Murray has still not won a match at Bercy Arena since lifting the title in 2016 en route to finishing as the year-end world number one.

The Briton saw three set points come and go before losing the first set in a tie-break, but bounced back to level the match and then take control.

But he twice failed to serve out the match, missing a match point in the 10th game.

De Minaur instead secured victory to set up a second-round tie with either Serbian lucky loser Dusan Lajovic or French wildcard Benjamin Bonzi.

Murray let slip two game points in the 12th and final game before being broken again, smashing his racquet in frustration when his exit was confirmed after three hours on court.

It was De Minaur’s fourth win over Murray this year.

Speaking after the defeat, Murray conceded he’s growing more and more frustrated with his performances and noticed an alarming trend that has crept into his game.

“It’s frustrating,” Murray said.

“I’m not really enjoying it just now, I would say, in terms of how I feel on the court and how I’m playing.

“The past five, six months haven’t been that enjoyable, which doesn’t help things, so I need to try and [get] some of that enjoyment back because playing a match like that, there’s not really much positivity there.

“When I play a good point, I’m not really getting behind myself and then, in the important moments, that will to win and fight that has always been quite a big, big part of my game.

“What happened today, I don’t remember it happening before. Those sorts of situations have happened quite a lot this year, and that’s not really me.

“It’s not enjoyable.”

Elsewhere on the first day of the tournament, US Open semi-finalist Ben Shelton lost 7-6 (7/4), 5-7, 6-3 to Alejandro Davidovich Fokina.

American 14th seed Frances Tiafoe lost 6-3, 6-4 to Alexander Bublik. The defeat ended Tiafoe’s slim hopes of reaching next month’s ATP Finals in Turin.

Karen Khachanov, the 2018 champion, progressed with a 6-4, 6-4 win over Australia’s Max Purcell