Head coach Harrison saw his side maintain their unbeaten start to their JD Cymru Premier season with a 6-2 victory over Flint Town United on Tuesday night.
Declan McManus, with a double, Chris Marriott, Adam Wilson, Leo Smith and substitute Jake Canavan were on target for Saints.
Saints, who have scored 13 goals in their last two league matches, have taken 19 from a possible 21 points so far this season.
The Park Hall side are currently three points clear at the top of the table with a game in hand on the three teams directly below them in the division’s top four.
Asked about having plenty of selection headaches ahead of the Newtown game, Harrison said: “That’s what I want. I want the players to make my job as hard as possible because if I’ve got a hard job they’re training well, they’re playing well.
“That’s their job and then my job is to pick the best team to win the football game.
“Myself and the staff will have a look at then again.”
Newtown, tonight’s visitors to Oswestry, are 10th in the table and lost 2-0 at home to Bala Town on Tuesday night. Saints drew 0-0 with Newtown at Latham Park in their opening league game of the season in August.
They are the only points TNS have dropped in the early weeks of the season, as they have since won six consecutive league games.
The Robins have suffered a difficult start to the season, winning just two of the opening seven games.