Davis, the 50 year old World Number 15, needed two snookers in the opening frame. But O'Sullivan, the World Number 4, was in a snooker when he fluked a red to win the frame.
Davis' first real chance came in the second frame. O'Sullivan was playing badly, but Davis was making bad mistakes. He missed a black from its spot, and O'Sullivan cleared to go 2-0 up. The third frame saw Davis make a 68 break and reduce his arrears to 2-1, again it was an O'Sullivan mistake that let the veteran in.
The fourth frame was another scrappy affair. Davis had chances, and looked like levelling at 2-2 until he missed a pink from the black spot. O'Sullivan then cleared the table to pinch the frame from Davis, and it was 3-1 at the interval. Davis should have been 3-1 up himself.
O'Sullivan returned after the interval but was again playing badly. Davis again missed an easy pot to leave O'Sullivan in, and he gratefully cleared up to take a 4-1 lead.
Davis then found some form, and was beginning to make fewer errors. It was O'Sullivan that began to take on rash shots, and Davis profited with two decent breaks in the two frames that followed, trailing only 4-3. Davis was still not on form himself though, missing an easy red with the rest in frame 7.
In the eighth frame, Davis again had an early chance that he failed to take. O'Sullivan continued to struggle, but he eventually won the frame, and clinch a 5-3 win.
Davis is struggling to stay in the top 16 for next season, with only two events, one in China, one the World Championship. He is ranked 29th provisionally, although he is set to improve upon that with his performance in Newport.