Australia\'s Neil Robertson defeated Welshman Mark Williams 6-4 to reach the Masters semi-finals at Alexandra Palace on Friday, setting up a clash with UK champion Judd Trump for a spot in the final. Williams battled back from 4-1 to 4-3 down, but a break of 119 to go 5-3 in front ended the Welshman\'s run as Robertson, the 2010 world champion, edged home. \"I potted some really good balls under pressure to go 5-3 up,\" Robertson told the BBC. The Melbourne player admitted he struggled with his tip during the match and would have to get it replaced before his semi-final. \"You are meant to play in a few tips and have one ready, but I haven\'t done it. Hopefully I can play it in tomorrow. A brand new tip is probably a player\'s worst nightmare,\" said the Australian. Trump beat Ronnie O\'Sullivan 6-2 in the quarter-finals and beat Robertson 9-7 in the semi-finals of the UK Championship last month. Asked how he sees his next match-up with Trump, Robertson said: \"I like to play attacking snooker, if I get in the balls I\'ll play quickly. \"He\'s playing really well, but players are getting opportunities against him.\"