Gaff, who has been the Eagles' substitute in four of his five senior games this season, had 34 possessions for South Fremantle last Saturday after being left out of the West Coast side that lost to Essendon by 16 points at Etihad Stadium.
Worsfold, who could also recall in-form midfielder Chris Masten, said 18-year-old Gaff had lived up to his reputation as an early draft pick and was capable of playing a full game in the high-stakes derby.
"It was a perfect hit-out for him, so there's nothing holding us back from playing him. It's all around selection," Worsfold said at a joint press conference with Fremantle coach Mark Harvey on Thursday morning.
"He has played that [substitute] role really well and if it was just around short-term stuff we'd keep playing him as the sub.
"But he's going to be better than that and we want him to be able to impact and play full games of footy.
"The best thing was for him to go back and play a full game for South Fremantle."
Gaff has averaged 11 disposals for West Coast, typically coming on late in matches and providing valuable run and carry.
Worsfold said Masten, who also had 34 possessions in his second WAFL game since returning from a knee injury, was "ready to go".
The Eagles have lost the last seven derbies, with their last win against Fremantle coming in round three, 2007.
After winning the first nine clashes against Fremantle the head-to-head ledger has tightened to 18-14 in West Coast's favour, and Worsfold agreed that a number of players were sick of losing to their cross-town rivals.
"Personally for me it's about this season, where we're at," he said.
"(But) I've heard several players comment publicly that they'd like to finish the run."
Worsfold said after an unsuccessful period that had seen the club finish out of the top eight for three consecutive years and collect its first wooden spoon, his team was now in better shape to challenge Fremantle.
It is the first derby since the Eagles' last win in early 2007 in which both sides are considered genuine finals contenders.
"[We're] probably in better form (and) I think just our squad's in better shape," Worsfold said. "That would be the biggest difference, to last year especially.
"Just having 'Glassy' (Darren Glass) back up and going, and in the last couple of years 'Coxy' (Dean Cox) hasn't been at peak fitness.
"Overall I think we're in a better position than we were last year and maybe the year before.
"The challenge is to try and match it with Fremantle and get a win on the board."
Nathan Schmook covers West Coast news for afl.com.au. Follow him on Twitter: @AFL_NSchmook
