GLASGOW, April 19 (Reuters) - Georgios Samaras earned champions Celtic a 1-0 win over Aberdeen that put them two points ahead of Rangers in the Scottish Premier League on Saturday. The Greek striker headed home in the 56th minute from 10 metres following a free kick by Barry Robson. But Celtic had to survive a first half scare when Scott Severin cracked a shot that hit both posts before landing in the arms of Polish keeper Artur Boruc in the fourth minute. Celtic top the standings with 77 points from 34 games while Rangers have 75 points from 31. Rangers face second division St Johnstone in their Scottish FA Cup semi-final on Sunday. Hamilton Accademical won promotion to the top flight for the first time in 19 years as second division champions after beating Clyde 2-0 on Saturday to clinch the title.