International duty has deprived Phoenix of Australian star striker Nathan Burns and New Zealanders Michael McGlinchey, Louis Fenton, Michael Boxall, Tom Doyle, Tyler Boyd and Joel Stevens for Sydney's visit to Westpac Stadium in Wellington.
Wellington (42, +16) are four points clear atop the table heading into round 23, with Melbourne Victory (+18), Sydney (+10) and Perth Glory (+7) - all 38 points - breathing down their necks.
Phoenix have taken the league by storm, winning four consecutive matches and Merrick believes his depleted team can maintain that form against Sydney, who are without Austria captain and A-League Golden Boot leader Marc Janko.
"I think where we're very strong [is] in midfield and I don't want to compromise midfield. That's a big part of my thinking," said Merrick when asked whether he would move Vince Lia back into defence.
"Let's not reduce our strength in one particular area, and move people around, when it's one position, it's a full-back's role. And given the number of experienced players we've got in the team, I think we could cope with a youngster and this is a time for a youngster to step up.
"Andrew Blake's doing really well, Matthew Ridenton's almost back to full fitness and young Tam Dimairo is doing really well. I like their competitiveness, they're comfortable on the ball and they understand the position really well.
"So I've got really good options, this isn't going to be a patched up team."
Lia is set to appear for the 150th time for the Phoenix, while opponent Sebastian Ryall, plus Scott Jamieson (Perth) and Josh Rose (Central Coast) will all reach 150 A-League outings during the weekend's matches.
Sunday's encounter comes after Victory and Glory's fixtures.
Victory, who have a game in hand, can close the gap at the summit with a win over Central Coast Mariners at AAMI Park on Friday.
Kevin Muscat's side could be without star striker Besart Berisha as the Albanian battles to overcome a strained quad.
As for Glory, they welcome lowly Western Sydney Wanderers to nib Stadium on Saturday attempting to arrest a nine-match winless streak.
Finals hopefuls Melbourne City and Brisbane Roar go head-to-head at AAMI Park on Saturday.
City occupy the sixth and only remaining finals spot, five points ahead of Roar, who are coming off a 4-1 loss at the hands of Western Sydney.
Cellar-dwelling Newcastle Jets and fifth-placed Adelaide United complete the round on Sunday.
