Andy Murray was visibly angry as he lost in the second round of the Qatar Open against Jakub Mensik on Wednesday.
The Brit repeatedly smashed his racket on the ground moments before his 18-year-old opponent saw out the biggest win in his career so far.
Murray got his week off to a perfect start on Tuesday, beating Frenchman Alexandre Muller to collect his first win since last October.
The 36-year-old had exited in the first round of the last four tournaments he had entered before this week.
Andy Murray was angry as he lost in the second round of the Qatar Open
Sky Sports
Murray overcame an issue with his knee on Tuesday with a straight-sets win to set up a clash against teenager Mensik.
But he was unable to back up his victory and was edged out in an extremely close encounter which went to a tie-break in all three sets.
With Mensik on match point at 6-4 up in the deciding tie-break, Murray vented his frustration by smashing his racket on the ground several times.
It didn't do anything to help his cause as Mensik saw out victory to progress to the quarter-final stage.
Czech youngster Mensik admitted he was left 'speechless' with his victory and admitted he knew most of the crowd wanted Murray to win.
He said: "I'm speechless right now. I know a lot of fans wanted Andy to win today.
"Andy is an unbelievable player. When I was young I watched him on TV winning Wimbledon.
"It's unbelievable at his age he's able to compete with the best players in the world so congratulations to him and all the best for the next tournament."
Mensik won the first set via a tie-break before Murray bounced back to win the second by the same manner.
The teen picked up an early break in the deciding set and then broke Murray for a second time to go 5-2 in front.
But Murray was not giving in and broke his opponent back twice when he was serving for the match to take the decider to another tie-break.
It was a fine effort to get back into the match but it was a step too far for the two-time Wimbledon champion.
LATEST SPORTS NEWS:
Andy Murray smashed his racket on the ground as Jakub Mensik closed out victory
Sky Sports
Murray hit eight aces to Mensik's 12, while he double-faulted on three occasions.
He vented his frustration on more than one occasion during the match, at one point shouting 'b******t' after losing a rally.
Mensik was pleased that he stayed calm towards the end of the match after missing two opportunities to serve out the win.
He added: "First set it was tough with the conditions, the wind started a little bit so the tie-break was not such a good quality.
Andy Murray was fuming as he lost the tie-break against Jakub Mensik
Sky Sports
"I was, in the end, a little bit lucky, so it's just great in the third set I was 5-2 and had two [service games].
"And then when it was 5-5 I said 'Go on, this guy cannot just give me any points'.
"But I tried to stay calm in the tie-break and I'm super happy that I stayed focused until the end."