They recruited midfielder Michael McGlinchey and striker Nathan Burns in the hope they would add more goals and both had good scoring chances in the opening 30 minutes but they were unable to convert their opportunities.
Burns, in particular, was guilty of blowing a one-on-one with Perth goalkeeper Danny Vukovic.
The former Phoenix custodian did well to get a hand to Burns' shot but there was no denying the Australian should have done better.
After a sustained period of dominance, Wellington were caught completely off guard when Perth nicked the game's opening goal as Irishman Andy Keogh smartly nodded home in the 32nd minute.
That goal silenced the crowd of 7767 and Wellington lost their zip as they meandered through the final stages of the opening spell and were probably glad to hear the halftime whistle so they could regroup.
Dutchman Roly Bonevacia was another off-season recruit of the Phoenix and he came to the capital with a good pedigree having come through the famed Ajax academy.
Deployed in a right-sided midfield role, his first couple of touches were heavy and he was given an early chance to strike a stinging volley from the top of the box but his shot didn't trouble Vukovic as it sailed out.
But Bonevacia warmed in to the game nicely and another newcomer, midfielder Alex Rodriguez, showed good intent to look for the ball as he strived to get involved.
The final member of the Fab Five is left back Tom Doyle who made a steady A-League debut before he was hooked after an hour and was replaced by Louis Fenton as Manny Muscat pushed to the other side of defence.
As the game wore on, Wellington's lack of goals appeared to frustrate the home side as they were unable to create many scoring opportunities.
Striker Jeremy Brockie is a player that fades in and out of games and Merrick may question if he got enough from the All White who wasn't able to impose himself on the contest.
Merrick will need the likes of Brockie to have greater involvement as the season progresses given he is playing in the centre of the forwards in Merrick's preferred 4-3-3 formation.
Eventually, Wellington's weight of possession told and they finally found a break through when Burns squared the ball for McGlinchey in the 73rd as the diminutive attacker scored.
As the Phoenix seem to have a habit of doing, their late goal sent the game towards a busy final 10 minutes as both teams searched for a winner.
It was the visitors that found it though in the 86th minute when a stray Vince Lia pass wasn't reeled in by Ben Sigmund and substitute Jamie Maclaren did the rest.
Perth Glory 2 (Andy Keogh 32, Jamie Maclaren 86) Wellington Phoenix 1 (Michael McGlinchey 72) halftime: 1-0
