Valencia, Spain, 23 October 2013 | AAP

A day after celebrating his 21st birthday, Bernard Tomic exited the Valencia Open when he retired from his first-round clash with Russian Mikhail Youzhny.

Tomic, Australia’s top-ranked men’s tennis player at 52 in the world, started with promise and won the first set on Tuesday.

But he struggled to recover from taking one of seven break points on offer in the second set, and eventually called it quits at 3-6 6-4 4-1.

It is the third consecutive first-round loss for Tomic, who went down to Jack Sock last week in Stockholm and Jeremy Chardy at the Shanghai Masters the week before that.

Tomic started the year by claiming his maiden ATP title, in Sydney, but has since struggled, although did enjoy a run to the fourth round at Wimbledon and a stellar year in Davis Cup.

He is expected to announce a new coach in the coming weeks, with father John currently suspended from the ATP circuit.

In other results in Valencia on Tuesday, fifth seed Jerzy Janowicz accounted for Spanish qualifier Pablo Carreno 7-5 7-6 (9-7) and Julien Benneteau defeated local Feliciano Lopez 6-3 6-1.