Shamrock Rovers got their season up and running with a comfortable first victory of the season over 10-man Dundalk at Oriel Park.The reigning league champions came into the game without a win in their opening six matches - five draws and one defeat - but were already a goal ahead through Rory Gaffney when the home side were reduced to 10 men on 31 minutes with Robbie Benson given the first red card of his professional career by referee Arnold Hunter.Rovers then doubled their lead through Lee Grace before Johnny Kenny and Graham Burke put the game to bed midway through the second half to ensure a first three points of the campaign for Stephen Bradley's side ahead of their Dublin derby tie away to Bohemians next Friday. FULL MATCH DETAILS Stephen O'Donnell’s side did their best to make a game of it after Benson’s dismissal but it took until two minutes from the end to test Alan Mannus.It was the visitors who threatened first on 13 minutes with Sean Kavanagh’s ball into Kenny seeing him fire just wide with Rory Gaffney’s follow up hitting the post.The Hoops then took the lead on 22 minutes with former Lilywhite Daniel Cleary floating a superb cross to the back post over the head of Archie Davies for Gaffney to race onto and head across Nathan Shepperd to the bottom right hand corner.Dundalk did have a golden chance to level six minutes later when Connor Malley slipped John Martin in on goal after a neat exchange with Benson but the former Waterford player couldn’t keep his effort down.That was to prove pivotal as Benson was dismissed on 31 minutes for a high challenge on Grace in front of the Rovers bench.The Hoops then responded by doubling their advantage on 36 minutes with Grace nodding home after Jack Byrne’s corner