* Scot downs Anderson in straight sets * Murray wary of next opponent Dimitrov (Recasts with quotes) By Clare Lovell LONDON, June 30 (Reuters) – Young gun Grigor Dimitrov stands between Andy Murray and the Wimbledon semi-finals and the champion is clearly wary of the Bulgarian he describes as “coming into his prime”. The Briton, who beat big-serving South African Kevin Anderson on Monday, has enjoyed a smooth run into the second week, playing within himself to reach the quarter-finals without dropping a set.