A day after he pleaded not guilty to raping a woman at three different spots in 20 minutes along a stretch of road, a 30-year-old man changed his mind and admitted his guilt.

Instead of continuing with his High Court trial in what prosecutors describe as a "brazen case", Lim Choon Beng pleaded guilty to two counts of rape, one count of sexual assault and one count of aggravated outrage of modesty. Four other charges will be considered during sentencing.

Deputy Public Prosecutor Zhuo Wenzhao told the court that Lim, who was jobless, was drinking with friends in Robertson Quay before he approached the victim along Martin Road at about 3am on Feb 9, 2013.

The 24-year-old woman from China, who worked as a performer at a lounge, was walking home alone from Havelock Road to her apartment. She slowed down to let Lim walk ahead of her.

After a short distance, Lim, then 26, turned around and spoke to her in English, before asking her in Mandarin if she was a Chinese national and if she liked American men.

Despite her attempts to shake him off, Lim grabbed her and pushed her backwards onto a grass patch in front of the Watermark condominium at about 3.15am.

The woman begged him to let her off, but he paid no heed and raped her.

When some cars passed by, Lim got off the victim. At about 3.25am, he pulled her across Rodyk Street and hit her head against a wall at the Robertson 100 condo.

The woman begged again to be freed but he raped her again.

Thinking that she could seek help from a security guard, the woman suggested that they go to her apartment. Meanwhile, a female security guard at The Inspira condo called the police after seeing Lim on top of the crying victim.

At about 3.35am, when Lim and the victim reached River Valley Close, he pinned her to the ground, forced her to perform oral sex on him and raped her again. This time, she managed to escape.

After running some distance, the victim stopped a car with a woman behind the wheel. She also contacted a friend to call the police.

When the victim returned to River Valley Close, she found police officers at the scene with Lim and immediately pointed him out as the person who had raped her.

The case has been adjourned to tomorrow for sentencing arguments. The maximum punishment for rape and sexual assault is 20 years' jail as well as caning or a fine.