Griffiths will be thrown into the fire tomorrow and will take a spot on the Phoenix's bench for their clash with the Melbourne Victory in Australia.
"The team's going really well. They're playing some great football. We've got some really good attacking options and if I can help out in any way, then great," Griffiths said. "I really think this team has some big ambition and hopefully I can contribute in some way."
Griffiths has left his wife and two children in Newcastle to join the Phoenix and there are no plans to play in the capital beyond this season as he is set up across the Tasman.
"At my age you sort of just plan week by week and go from there. But my body feels good. I haven't had any major injuries and I can still keep up with these young whippersnappers."
Griffiths will probably be used in a super-sub role behind frontmen Nathan Burns, Roy Krishna and Michael McGlinchey for the rest of the summer.
Defender Louis Fenton won't be in the squad for tomorrow's game because of the concussion he suffered a fortnight ago. Manny Muscat missed training yesterday as his wife was due to give birth soon but he was expected to suit up against the Victory.
Wellington are in fourth place on the A-League ladder and their next three games are against the teams who are above them. After meeting the Victory tomorrow they host Adelaide next week before a trip to Perth on March 14.
"It's crucial, it'll be a real yardstick of where we're at," Merrick said.
Meanwhile, Capital Football development manager Des Buckingham will coach the Phoenix's goalkeepers for the rest of the season following the departure of Jonathan Gould, who has joined English Premier League club West Bromwich Albion.