The hosts are winless in their last eight league games, while Istanbulspor have lost all of their previous four matches.
Match preview
Since beginning the season with two wins from three games, Giresunspor have been unable to record a victory in any of their last eight league games.
In their most recent encounter, they were comfortably beaten 3-1 by Istanbul Basaksehir, with Serginho scoring a late consolation for his side.
With nine points to their name after 11 matches, Giresunspor are only one point adrift of safety ahead of Saturday's contest.
If they are to move out of the relegation zone then the league's joint-lowest scorers will need to improve in the final third after scoring only eight goals this season.
They will also be aware of the importance of scoring first as they have lost six of the seven games in which they have conceded the opening goal.
Like their hosts, Istanbulspor have also won only two league games this season, and as a result of their poor form, Osman Zeki Korkmaz decided to leave his position as manager.
Fatih Tekke has replaced Korkmaz in the dugout, but his third spell as Istanbulspor boss did not begin on a positive note, as he oversaw a 5-2 home defeat to Fenerbahce.
Jetmir Topalli netted a brace for his side, but a Michy Batshuayi hat-trick as well as goals from Irfan Kahveci and Enner Valencia ensured Istanbulspor are still winless at home this season.
After losing for the fourth straight game, Istanbulspor are currently one place behind their opponents, with two points separating them from safety.
Although they have lost their last two away fixtures, the visitors can take confidence from the fact that they have picked up seven of their eight points this season from away games.
Giresunspor Turkish Super Lig form:
D
D
L
L
D
L
Giresunspor Turkish Super Lig form:
Istanbulspor Turkish Super Lig form:
D
W
L
L
L
L
Istanbulspor form (all competitions):
Team News
Keles could make a couple of changes to his Giresunspor side following the 3-1 defeat to Istanbul Basaksehir last weekend.
Alper Uludag is expected to return to the starting lineup after serving a one-match suspension, while Murat Cem Akpinar could be brought into midfield.
Riad Bajic will retain his place up front, and the forward will be looking to add to the three goals he has scored this season.
As for the visitors, they are still without the services of Eslem Ozturk, who is currently sidelined with a knee injury.
Eduart Rroca missed the defeat to Fenerbahce through suspension, but the midfielder could return to the side for Saturday's contest.
After scoring two goals last weekend, Topalli is expected to retain his place on the right flank, while Valon Ethemi will operate on the left wing, and the pair will provide support for Ibrahim Yilmaz, who is set to lead the line.
Giresunspor possible starting lineup:
Piri; Bilazer, Arias, Perez, Uludag; Akpinar, Campuzano; Serginho, Saglam, Sainz; Bajic
Istanbulspor possible starting lineup:
Jensen; Berber, Erdogan, Mehremic, Yasar; Topalli, Kabasakal, Rroca, Sarikaya, Ethemi; Yilmaz