Johanna Konta suffered a shock loss to Serbia’s Aleksandra Krunic in the opening round of the US Open.

After Andy Murray’s withdrawal, Britain’s hopes predominantly rested on the shoulders of the world No.7.

Konta’s brilliant run to the semi-finals of Wimbledon marked her out as a contender for the title in New York on her favoured hard courts and she went into the tournament as one of eight players in the race to be world No.1.

But the 26-year-old never looked comfortable against 78th-ranked Krunic and lost 4-6 6-3 6-4 in two hours and 17 minutes.

Konta insisted she felt happy with her preparation despite only winning two matches in the build-up to the tournament having taken a short break after Wimbledon.

Krunic looked a good draw on paper, but the Serbian showed how dangerous she can be here three years ago when she defeated Madison Keys and Petra Kvitova on her way to the fourth round.

She has done little of note since, but is a fearless ball striker and a player who can take advantage of a big name having a bad day.

It did not seem that way initially when Konta, who made the fourth round the last two years, eased into a 4-1 lead in the first set on a sleepy Grandstand court.

Krunic took advantage of some errors from the British number one to pull back level at 4-4 but then double-faulted for a fifth time to lift the pressure before Konta served out the set. But there was no fluency from the 26-year-old and, as her first-serve percentage dipped well below 50, Krunic began to step in and take control.

The Serbian reeled off three games in a row to win the second set and had Konta in real trouble when a double fault put her a break down at 1-2 in the decider.

The world number seven dug her heels in to draw level but then dropped serve again as Krunic sensed the scalp was hers for the taking.

Konta at least forced the 24-year-old to serve it out but there were no nerves as she powered her way to three match points, taking the second when her opponent pulled a backhand well wide - her 42nd unforced error.