Prosecuting, Maryam Syed KC, said the singer had been "engaging in consensual sexual activity" with one woman, but he allegedly removed his condom, and she "repeatedly told Mr Johnston to stop" but he did not.
The other woman told police she engaged in consensual sex with the singer and asked him to use a condom, the court heard.
The woman said she started to feel his hands around her neck and "no matter how many times she removed them", he kept putting his hands back around her throat, Ms Syed said.
It was alleged he then stopped and removed the condom, then carried on with the sex.
Mr Johnston described his lovemaking as "fast, energetic, maybe a bit passionate" but said he was never aggressive, always used a condom and that the sex was consensual.
He previously told the jury: "I did not rape those two girls."
Ms Syed put it to Mr Johnston that it is his case that these two women had stood in the witness box "and told this jury a pack of lies".
The singer, who landed a lucrative record deal with Simon Cowell, released an album that went to number four in the UK charts and appeared on tour with other Britain's Got Talent finalists.