Emma Raducanu's disappointing run since her shock US Open triumph continued at the Guadalajara Open when the top seed retired with a hip injury in her first round match against Australia's Daria Saville.

Raducanu had won the first set 7-5 and served for the match at 5-3 but the 610th ranked Saville broke her and went on to level the match in a tie-break 7-6 (7/4).

Raducanu called it a day when a break down at 3-4 in the deciding set after 3 hours and 36 minutes -- the longest match so far on the WTA Tour this year.

Their tussle edged the 3 hours and 9 minutes which Montenegro's Danka Kovinic took to beat Jang Su-Jeong 6-3 2-6 6-4 in the first round of the Australian Open.

Raducanu's latest setback follows her three set second round loss in the Australian Open to the 98th ranked Kovinic, when  the Briton hindered by a blister on her right hand.

"This is probably the first match in a long time when I felt like I was being myself," said Saville, who was ranked as high as 20 before an Achilles tendon injury halted her progress.

"I was being feisty Dasha. I just want to keep on working and keep on going here."

Raducanu -- who was playing her first match since the Australian Open -- has failed to build on her extraordinary triumph at Flushing Meadow last September.

In her five tournaments up to this week's Guadalajara Open her best run was into the quarter-finals of the Tranyslvanian Open last October.

On Wednesday, it emerged that a London court had issued a restraining order against a man convicted of stalking Raducanu.