Mark Selby came from 4-0 down to beat Neil Robertson 6-4 in their quarter-final at the UK Championship in a match that finished after midnight.
The key frame was the 49-minute ninth, which after an intense battle Selby took, and when Robertson left him a cheap opening red early in the next frame the Leicester man made a match-winning 101 break.
Selby punched the air in celebration after potting the red that made the win safe and victory was completed at 12.05am.
He will take on Mark Davis in the last four and will go back to number one if he makes it through to the final. Selby relinquished top spot to Judd Trump in November.
Davis, enjoying the most successful season of his 21-year career, edged out Matthew Stevens 6-4 in his quarter-final.
The 40-year-old Hastings man reached his third ranking event semi-final of the year with a performance that included breaks of 101, 80 and 70.