Ronnie O'Sullivan booked his place in the last four of the German Masters with a 5-3 win over Matthew Stevens.
The three-time world champion, seeking his first ranking event title in two years, won four frames in a row to come from 3-1 down to beat the Welshman.
The world number 16 recovered from 0-4 to beat Andrew Higginson in his opener, before cruising past Joe Perry 5-1.
Former world number one O'Sullivan, 36, will now play Stephen Lee while Shaun Murphy faces Scot Stephen Maguire.
World number six Murphy recorded a 5-3 win over former Crucible finalist Mark Selby and former UK champion Maguire edged out last year's World Championship runner-up Judd Trump 5-4.
Bristol's Trump wasted a good chance in the decider and Maguire cleared to the black to cement his spot in the semi-finals.
Earlier in the tournament, O'Sullivan had looked in danger of slipping out of the top 16 and surrendering his automatic place in the World Championship after a sluggish start against Higginson.
But his pass to the main draw at the Crucible now appears safe with the Welsh Open, beginning on 13 February, the last ranking event to count towards seeding for the World Championship, which starts on 21 April.