Alan Garforth, 67, admitted offences of sexual assault and and sexual assault by penetration at Burnley Crown Court on Monday, July 26.
A woman in her 20s reported being attacked at Garforth's address in Blackpool after he provided her with a massage in October 2018.
Garforth, of Pavey Close, was arrested and later received summons to appear at court in connection with the offences.
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He pleaded guilty and will be sentenced on September 20 at Burnley Crown Court.
Det Sgt Nicole Ryder-Jones, of Blackpool Police, said: "Garforth's actions were predatory and sexually motivated. We welcome him admitting his guilt.
"I must praise the victim and thank her for coming forward. She has shown great courage and strength in reporting the crimes to police.
"I hope this case will give other victims of sexual offending the confidence to come forward, knowing that we will listen to them and act on the information they provide."
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