By Steve Keating MIAMI (Reuters) - Six-times Miami champion Serena Williams and five-times runner-up Maria Sharapova remained on another Sony Open collision course after each recorded fourth-round wins on Monday. While Williams and Sharapova clashed in last year's final there will be no championship rematch on Saturday at Crandon Park with the American and Russian on the same side of the draw and closing in on a semi-final showdown. After getting her title defence off to a slow start world number one Williams, who lives an hour's drive from the Crandon Park Tennis Center and considers the event her home tournament, stepped it up a gear against Coco Vandeweghe sweeping past the young American qualifier 6-3 6-1 in 79 minutes. That kind of helped out, too." Fourth seed Sharapova got a much-needed wake-up call after sleep-walking her way through the opening set before dispatching Belgian Kirsten Flipkens 3-6 6-4 6-1. Click here to read full news..