North Queensland were without the trio for the round two 3-1 loss to Sunshine Coast, as injuries decimated the Razorbacks, reducing their 20-man squad to 13.
Coach Mick Tonner said they would be in a far healthier position this week.
"Just that week off has enabled us to get a few troops back on deck," he said.
"It's given us some time to get over some injuries and from the 20-man squad we actually have 16 players to choose from for the trip to Redlands on Saturday."
Promising young striker Brett Hay (back) is still out of action along with Aaron Walker, who is booked in to undergo surgery on his troublesome knee next week.
Lorenzo Sipi (knee) is still three or four weeks away from a return, while Hayden Beale will be missing for the next two games after being suspended for his last-start send off.
However Tonner said the return of Sapelli, in particular, would come as a major boost for the Razorbacks as they look to improve on their one-win, one-loss start to the season.
He said the captain's return to training had had an immediate impact on team morale.
"Sapa' is a huge boost. His leadership on the park, we desperately need `Sapa', he's a very important part of our team," Tonner said.
"Last night's training, we trained exceptionally well.
"Just having the boys back ... you can tell there is a game around the corner, everyone's sort of buzzing and having `Sapa' there – whether it's subconscious or not – the standard of our training was a lot better."
He said the returns of Navarro and Rowell should not be underestimated either.
"Jake Navarro gives us a little bit of muscle off the bench and he complements David Mayes's game very, very well," Tonner said.
"I haven't really decided with regards to Jimmy Artis and Luke Rowell what the starting team will be, but I do know that `Sapa' will come in and Jake Navarro will come on to the bench."
Tonner will finalise the team to take on the Devils after training tonight.