King said his 1sts side is looking forward to playing on the well-maintained Massey grounds, but having made up a distance of three points on the Rangers in second place, they must not succumb to a mid-season lag coming off a great effort last weekend.
Athletic beat Massey 4-0 in the first round at Wembley, but this week's home team have been good enough to earn draws with Rangers, Red Sox Manawatu and PN Marist since then.
Ismael Mimbi is their main attacker with six goals, while three other players have got two.
"Last time, it certainly wasn't an easy game, they fought very hard," said King.
"Looking at their results, they are starting to get some goals now.
"We have to make sure we carry on. The never-give-up, never-say-die mentality."
Having surprised the rest of the League by picking up four wins and a draw this season after a poor 2016, Athletic are aware they are transitioning from the hunters to the hunted.
"You see it all the time. Teams in the middle of the table and you're wondering, 'what are they doing there?'," said King.
"We've got to be conscious of that, while we're sitting in the top half of the table, people are now trying to knock us off."
Athletic have reshuffled the deck for their two games, as King is looking to take a three-man bench to Massey by adding Jordan Candish, who scored in the Reserves win, youngest player Jake Simcox, and Jai Stephens, who has floated between the two squads.
Staying home to play for the Reserves will be 1sts regulars Raymond Hove and Scott Burney, due to work and young family commitments respectively.
Collectively, they have contributed 10 goals to the 1sts this season, and so will greatly assist the Reserves chances against Feilding United, adding to a leadership group with includes Richard Dalby in the middle of the field.
"Having those guys on the park tomorrow, I think, is important to use their experience to negate the nerves," said King.
"[Feilding] like to play for the whole game, it's going to be a challenge for our younger team."
Now sitting a point behind the Reserves in seventh spot, Feilding may have only three wins and a draw, yet their points differential from five losses is only -5, showing they will fight for every yard.
The Big Orange Wanganui City 1sts learned that when they got out of jail with a 2-1 win over Feilding two weeks ago, but the malaise within the squad did not dissipate as they surrendered their unbeaten tag to Breakers RSM Rovers 2-1 at home last Saturday.
They still lead the table outright only by virtue of the Athletic Reserves doing them a massive favour by upsetting Hokowhitu.
For City coach Kelvin Francis, enough was enough, as he organised a special team meeting at the Sport Whanganui offices on Monday.
The boys had a drink and some nibbles together, as they were encouraged to speak freely about how the squad was going, the coach explained.
"Just a real debrief and 'right-o, lads, this is what we want to achieve'."
It led to a strong training session as they prepare to travel to Skoglund Park to take on eighth-placed North End for the first time after the April 8 game was rained out.
"They are a team that traditionally in the past played real good football," said Francis.
While glad to still be leading the competition with the second round Hokowhitu game looming, Francis said if his side had to be beaten, he would rather it was by a team that played well on the day, instead of his side letting themselves down.
"Back to basics. We didn't talk to each other on the field last week, we were a bit flat.
"We got away with it [on table], to be fair.
"It's not often a team goes through unbeaten."
Top goal scorer Anthony Bell is still nursing his quad strain, while Cameron Hussey is unavailable this week due to a work trip to Nelson, on top of the loss of Carl Bond with a meniscus tear.
Coming up last weekend, Dan Aplin will stay with the side after scoring their sole goal.
"Dan is getting into the flow of how they play. The boys had a good chat with him," said Francis.
In addition, the coach has added Zane Robinson, who has recently been playing rugby for Marist Celtic, but has a ten year history with the City club.
Today's match will also be a homecoming for Robinson, as he played for North End as a junior, at a time where he was getting attention for possible New Zealand age-group honours.
"He's a calming influence in the middle of the field," said Francis.
All games start at 2.45pm.
