Sean O'Connor and Marty Waters responded to one of Pat Fenlon's pre-season demands with a goal apiece as newly-promoted Longford's honest endeavour got no reward for the second week running.
Frustrated in his efforts to sign a second experienced striker in the close season to complement Danny Nort, Fenlon was delighted to see his wingers get on the scoresheet.
Though Longford started brightly, a goal out of nothing brought Rovers a 24th minute lead. O'Connor was given too much time and space some 25 yards out and his dipping left-foot shot seemed to deceive goalkeeper Paul Hunt.
Longford had a shout for a penalty ignored before sloppy defending let Waters in for Rovers' second on 41 minutes.
Longford Town - Hunt; Mulhall, Flynn, Tyrell (Rossiter, 71), Powell; Shaw, O'Connor, Salmon (Gorman, 84), Rice, Deady (Cowan, h/t); O'Sullivan.
SHAMROCK ROVERS - Hyland; Madden, Webster, Kenna, Byrne; S. O'Connor (Drennan, 66), Fahey, McPhail, Waters; McCabe; North (R. Brennan, 83).
ref - P Sutton (Clare).
Longford Town 0
Shamrock Rovers 2