De Silva, 29, has been charged with sexual violation by unlawful sexual connection after an incident at a Christchurch flat in the early hours of November 11, 2018.
De Silva, also known as Chris, pleaded not guilty to the charge in the Christchurch District Court this morning.
The complainant had moved from the living room to her boyfriend's bedroom after the latter had passed out on the couch and was unable to be woken. There, she alleges De Silva entered the bedroom while she slept and performed a sexual act on her.
The Crown prosecutor said the complainant admitted she was very drunk and had partially woken up to the accused sexually violating her.
She only fully woke up, when he started to kiss her, the crown alleged. It was then she realised it wasn't her boyfriend.
De Silva's lawyer Sean McManus said the defence would maintain the complainant was awake when the sexual connection occurred.
McManus said the complainant had given consent when De Silva had suggested himself as an alternative because her boyfriend was asleep.
The jury trial started Monday August 3 and is expected to last the week.