The 20-year-old girl was battling for life in a hospital while the attacker is out of danger.
The shocking incident occurred in a lodge at Chaitanyapuri under the limits of Rachakonda police commissionerate on the city outskirts.
Police suspect that Venkatesh and Manasvi, both undergoing coaching for a competitive exam, had met at the lodge to resolve some differences and during an altercation, he attacked her with the knife.
The girl, hailing from Meerpet near Hyderabad, sustained a deep cut on her throat. She was admitted to a private hospital, where her condition is stated to be critical.
Police said the preliminary investigations revealed that Venkatesh, a native of Nellore district of Andhra Pradesh, had rented a room at the lodge and called Manasvi there. He was allegedly unhappy with her for getting closer to someone else.
They spent nearly two hours in the room and had a heated argument. After hearing thhe girl's cries from the room, a lodge employee alerted his other colleagues. They entered the room and saw the girl lying in pool of blood. Venkatesh, who also tried to kill himself by cutting his wrist, was shifted to government-run Osmania Hospital.
The investigations also revealed that Manasvi suspected some trouble after reaching the lodge and noticing a change in Venkatesh's behaviour. She had sent a message to her father on WhatsApp and also shared her location. However, by the time her father reached there, Venkatesh had carried out his brutal attack.
( With inputs from IANS )