Fennelly injured his ankle in a club game last month and had been wearing a surgical boot, but he played a full part in training last night at Nowlan Park and could now be set for a recall.
Henry Shefflin, also suffering from an ankle injury, will not make the Dublin game but he is back jogging, while Jackie Tyrrell could also miss out on Sunday as he is struggling with a quad muscle injury.
Elsewhere, Shane Fives will make his championship debut at corner-back in Waterford’s away All-Ireland qualifier phase one clash with Offaly at O’Connor Park in Tullamore on Saturday evening.
Déise manager Michael Ryan has made three changes to the side which lost to Clare in the Munster championship. Fives replaces Brian O’Halloran while Stephen O’Keeffe is named in goal as Ian O’Regan misses out and Brian O’Sullivan receives his first championship start at corner-forward since the 2011 Munster final as he takes the place of Ballygunner colleague Pauric Mahony.
There is also a fresh midfield pairing with captain Kevin Moran partnering Paudie Prendergast. Jamie Nagle remains an injury worry after he sustained a shoulder injury in a challenge match against the county U21s last Sunday.
Meanwhile, Tipperary senior football manager Peter Creedon is planning without leading forward Barry Grogan for the All-Ireland SFC qualifier against Galway on Saturday week, June 29, after he broke a finger playing for Aherlow in an intermediate club hurling game last weekend.
WATERFORD (SH v Offaly): S O’Keeffe (Ballygunner); S Fives (Carrigtwohill, Cork), L Lawlor (Fourmilewater), N Connors (Passage); J Nagle (Dungarvan), M Walsh (Stradbally), D Fives (Tourin); P Prendergast (Lismore), K Moran (De La Salle); J Dillon (De La Salle), S Prendergast (Ardmore), S O’Sullivan (Ballygunner); J Barron (Fourmilewater), M Shanahan (Lismore), B O’Sullivan (Ballygunner).