Horwill missed all of the last international season after being injured in May last year, but he is expected to be back to full fitness for the arrival of the British and Irish Lions in June.
"I'm a terrible spectator at the best of times, so it's a huge relief to be out of team rehab and in a position to play once again," Horwill told reporters.
"We've been extremely diligent in not rushing the rehab process to ensure that my hamstring would be ready for when the Super Rugby season kicked off. It's exciting to now be at that stage and I'm just looking forward to Friday night."
However, scrum-half Will Genia will miss the opening rounds through injury.